pub struct Vec<T, A = Global>where
A: Allocator,{ /* private fields */ }
Expand description
A contiguous growable array type, written as
Vec<T>
, short for ‘vector’.
Examples
let mut vec = Vec::new();
vec.push(1);
vec.push(2);
assert_eq!(vec.len(), 2);
assert_eq!(vec[0], 1);
assert_eq!(vec.pop(), Some(2));
assert_eq!(vec.len(), 1);
vec[0] = 7;
assert_eq!(vec[0], 7);
vec.extend([1, 2, 3]);
for x in &vec {
println!("{x}");
assert_eq!(vec, [7, 1, 2, 3]);
Run
The
vec!
macro is provided for convenient initialization:
let mut vec1 = vec![1, 2, 3];
vec1.push(4);
let vec2 = Vec::from([1, 2, 3, 4]);
assert_eq!(vec1, vec2);
Run
It can also initialize each element of a
Vec<T>
with a given value.
This may be more efficient than performing allocation and initialization
in separate steps, especially when initializing a vector of zeros:
let vec = vec![0; 5];
assert_eq!(vec, [0, 0, 0, 0, 0]);
// The following is equivalent, but potentially slower:
let mut vec = Vec::with_capacity(5);
vec.resize(5, 0);
assert_eq!(vec, [0, 0, 0, 0, 0]);
Run
For more information, see Capacity and Reallocation .
Use a
Vec<T>
as an efficient stack:
let mut stack = Vec::new();
stack.push(1);
stack.push(2);
stack.push(3);
while let Some(top) = stack.pop() {
// Prints 3, 2, 1
println!("{top}");
}
Run
Indexing
The
Vec
type allows to access values by index, because it implements the
Index
trait. An example will be more explicit:
let v = vec![0, 2, 4, 6];
println!("{}", v[1]); // it will display '2'
Run
However be careful: if you try to access an index which isn’t in the
Vec
,
your software will panic! You cannot do this:
Use
get
and
get_mut
if you want to check whether the index is in
the
Vec
.
Slicing
A
Vec
can be mutable. On the other hand, slices are read-only objects.
To get a
slice
, use
&
. Example:
fn read_slice(slice: &[usize]) {
// ...
let v = vec![0, 1];
read_slice(&v);
// ... and that's all!
// you can also do it like this:
let u: &[usize] = &v;
// or like this:
let u: &[_] = &v;
Run
In Rust, it’s more common to pass slices as arguments rather than vectors
when you just want to provide read access. The same goes for
String
and
&str
.
Capacity and reallocation
The capacity of a vector is the amount of space allocated for any future elements that will be added onto the vector. This is not to be confused with the length of a vector, which specifies the number of actual elements within the vector. If a vector’s length exceeds its capacity, its capacity will automatically be increased, but its elements will have to be reallocated.
For example, a vector with capacity 10 and length 0 would be an empty vector
with space for 10 more elements. Pushing 10 or fewer elements onto the
vector will not change its capacity or cause reallocation to occur. However,
if the vector’s length is increased to 11, it will have to reallocate, which
can be slow. For this reason, it is recommended to use
Vec::with_capacity
whenever possible to specify how big the vector is expected to get.
Guarantees
Due to its incredibly fundamental nature,
Vec
makes a lot of guarantees
about its design. This ensures that it’s as low-overhead as possible in
the general case, and can be correctly manipulated in primitive ways
by unsafe code. Note that these guarantees refer to an unqualified
Vec<T>
.
If additional type parameters are added (e.g., to support custom allocators),
overriding their defaults may change the behavior.
Most fundamentally,
Vec
is and always will be a (pointer, capacity, length)
triplet. No more, no less. The order of these fields is completely
unspecified, and you should use the appropriate methods to modify these.
The pointer will never be null, so this type is null-pointer-optimized.
However, the pointer might not actually point to allocated memory. In particular,
if you construct a
Vec
with capacity 0 via
Vec::new
,
vec![]
,
Vec::with_capacity(0)
, or by calling
shrink_to_fit
on an empty Vec, it will not allocate memory. Similarly, if you store zero-sized
types inside a
Vec
, it will not allocate space for them.
Note that in this case
the
Vec
might not report a
capacity
of 0
.
Vec
will allocate if and only
if
mem::size_of::<T>
() *
capacity
() > 0
. In general,
Vec
’s allocation
details are very subtle — if you intend to allocate memory using a
Vec
and use it for something else (either to pass to unsafe code, or to build your
own memory-backed collection), be sure to deallocate this memory by using
from_raw_parts
to recover the
Vec
and then dropping it.
If a
Vec
has
allocated memory, then the memory it points to is on the heap
(as defined by the allocator Rust is configured to use by default), and its
pointer points to
len
initialized, contiguous elements in order (what
you would see if you coerced it to a slice), followed by
capacity
-
len
logically uninitialized, contiguous elements.
A vector containing the elements
'a'
and
'b'
with capacity 4 can be
visualized as below. The top part is the
Vec
struct, it contains a
pointer to the head of the allocation in the heap, length and capacity.
The bottom part is the allocation on the heap, a contiguous memory block.
ptr len capacity
+--------+--------+--------+
| 0x0123 | 2 | 4 |
+--------+--------+--------+
Heap +--------+--------+--------+--------+
| 'a' | 'b' | uninit | uninit |
+--------+--------+--------+--------+
uninit represents memory that is not initialized, see MaybeUninit
.
Note: the ABI is not stable and Vec
makes no guarantees about its memory
layout (including the order of fields).
Vec
will never perform a “small optimization” where elements are actually
stored on the stack for two reasons:
It would make it more difficult for unsafe code to correctly manipulate
a Vec
. The contents of a Vec
wouldn’t have a stable address if it were
only moved, and it would be more difficult to determine if a Vec
had
actually allocated memory.
It would penalize the general case, incurring an additional branch
on every access.
Vec
will never automatically shrink itself, even if completely empty. This
ensures no unnecessary allocations or deallocations occur. Emptying a Vec
and then filling it back up to the same len
should incur no calls to
the allocator. If you wish to free up unused memory, use
shrink_to_fit
or shrink_to
.
push
and insert
will never (re)allocate if the reported capacity is
sufficient. push
and insert
will (re)allocate if
len == capacity
. That is, the reported capacity is completely
accurate, and can be relied on. It can even be used to manually free the memory
allocated by a Vec
if desired. Bulk insertion methods may reallocate, even
when not necessary.
Vec
does not guarantee any particular growth strategy when reallocating
when full, nor when reserve
is called. The current strategy is basic
and it may prove desirable to use a non-constant growth factor. Whatever
strategy is used will of course guarantee O(1) amortized push
.
vec![x; n]
, vec![a, b, c, d]
, and
Vec::with_capacity(n)
, will all produce a Vec
with exactly the requested capacity. If len == capacity
,
(as is the case for the vec!
macro), then a Vec<T>
can be converted to
and from a Box<[T]>
without reallocating or moving the elements.
Vec
will not specifically overwrite any data that is removed from it,
but also won’t specifically preserve it. Its uninitialized memory is
scratch space that it may use however it wants. It will generally just do
whatever is most efficient or otherwise easy to implement. Do not rely on
removed data to be erased for security purposes. Even if you drop a Vec
, its
buffer may simply be reused by another allocation. Even if you zero a Vec
’s memory
first, that might not actually happen because the optimizer does not consider
this a side-effect that must be preserved. There is one case which we will
not break, however: using unsafe
code to write to the excess capacity,
and then increasing the length to match, is always valid.
Currently, Vec
does not guarantee the order in which elements are dropped.
The order has changed in the past and may change again.
Implementations
§
source
§
impl<T>
Vec
<T,
Global
>
source
§
impl<T>
Vec
<T,
Global
>
source
pub fn
with_capacity
(capacity:
usize
) ->
Vec
<T,
Global
>
source
pub fn
with_capacity
(capacity:
usize
) ->
Vec
<T,
Global
>
Constructs a new, empty
Vec<T>
with at least the specified capacity.
The vector will be able to hold at least
capacity
elements without
reallocating. This method is allowed to allocate for more elements than
capacity
. If
capacity
is 0, the vector will not allocate.
It is important to note that although the returned vector has the
minimum
capacity
specified, the vector will have a zero
length
. For
an explanation of the difference between length and capacity, see
Capacity and reallocation
.
If it is important to know the exact allocated capacity of a
Vec
,
always use the
capacity
method after construction.
For
Vec<T>
where
T
is a zero-sized type, there will be no allocation
and the capacity will always be
usize::MAX
.
Panics
Panics if the new capacity exceeds
isize::MAX
bytes.
Examples
let mut vec = Vec::with_capacity(10);
// The vector contains no items, even though it has capacity for more
assert_eq!(vec.len(), 0);
assert!(vec.capacity() >= 10);
// These are all done without reallocating...
for i in 0..10 {
vec.push(i);
assert_eq!(vec.len(), 10);
assert!(vec.capacity() >= 10);
// ...but this may make the vector reallocate
vec.push(11);
assert_eq!(vec.len(), 11);
assert!(vec.capacity() >= 11);
// A vector of a zero-sized type will always over-allocate, since no
// allocation is necessary
let vec_units = Vec::<()>::with_capacity(10);
assert_eq!(vec_units.capacity(), usize::MAX);
Run
source
pub unsafe fn
from_raw_parts
(
ptr:
*mut T
,
length:
usize
,
capacity:
usize
) ->
Vec
<T,
Global
>
source
pub unsafe fn
from_raw_parts
(
ptr:
*mut T
,
length:
usize
,
capacity:
usize
) ->
Vec
<T,
Global
>
Creates a
Vec<T>
directly from a pointer, a capacity, and a length.
Safety
This is highly unsafe, due to the number of invariants that aren’t
checked:
ptr
must have been allocated using the global allocator, such as via
the
alloc::alloc
function.
T
needs to have the same alignment as what
ptr
was allocated with.
(
T
having a less strict alignment is not sufficient, the alignment really
needs to be equal to satisfy the
dealloc
requirement that memory must be
allocated and deallocated with the same layout.)
The size of
T
times the
capacity
(ie. the allocated size in bytes) needs
to be the same size as the pointer was allocated with. (Because similar to
alignment,
dealloc
must be called with the same layout
size
.)
length
needs to be less than or equal to
capacity
.
The first
length
values must be properly initialized values of type
T
.
capacity
needs to be the capacity that the pointer was allocated with.
The allocated size in bytes must be no larger than
isize::MAX
.
See the safety documentation of
pointer::offset
.
These requirements are always upheld by any
ptr
that has been allocated
via
Vec<T>
. Other allocation sources are allowed if the invariants are
upheld.
Violating these may cause problems like corrupting the allocator’s
internal data structures. For example it is normally
not
safe
to build a
Vec<u8>
from a pointer to a C
char
array with length
size_t
, doing so is only safe if the array was initially allocated by
a
Vec
or
String
.
It’s also not safe to build one from a
Vec<u16>
and its length, because
the allocator cares about the alignment, and these two types have different
alignments. The buffer was allocated with alignment 2 (for
u16
), but after
turning it into a
Vec<u8>
it’ll be deallocated with alignment 1. To avoid
these issues, it is often preferable to do casting/transmuting using
slice::from_raw_parts
instead.
The ownership of
ptr
is effectively transferred to the
Vec<T>
which may then deallocate, reallocate or change the
contents of memory pointed to by the pointer at will. Ensure
that nothing else uses the pointer after calling this
function.
Examples
use std::ptr;
use std::mem;
let v = vec![1, 2, 3];
// Prevent running `v`'s destructor so we are in complete control
// of the allocation.
let mut v = mem::ManuallyDrop::new(v);
// Pull out the various important pieces of information about `v`
let p = v.as_mut_ptr();
let len = v.len();
let cap = v.capacity();
unsafe {
// Overwrite memory with 4, 5, 6
for i in 0..len {
ptr::write(p.add(i), 4 + i);
// Put everything back together into a Vec
let rebuilt = Vec::from_raw_parts(p, len, cap);
assert_eq!(rebuilt, [4, 5, 6]);
}
Run
Using memory that was allocated elsewhere:
#![feature(allocator_api)]
use std::alloc::{AllocError, Allocator, Global, Layout};
fn main() {
let layout = Layout::array::<u32>(16).expect("overflow cannot happen");
let vec = unsafe {
let mem = match Global.allocate(layout) {
Ok(mem) => mem.cast::<u32>().as_ptr(),
Err(AllocError) => return,
mem.write(1_000_000);
Vec::from_raw_parts_in(mem, 1, 16, Global)
assert_eq!(vec, &[1_000_000]);
assert_eq!(vec.capacity(), 16);
}
Run
source
§
impl<T, A>
Vec
<T, A>
where
A:
Allocator
,
source
§
impl<T, A>
Vec
<T, A>
where
A:
Allocator
,
source
pub const fn
new_in
(alloc: A) ->
Vec
<T, A>
🔬
This is a nightly-only experimental API. (
allocator_api
#32838
)
source
pub const fn
new_in
(alloc: A) ->
Vec
<T, A>
allocator_api
#32838
)
source
pub fn
with_capacity_in
(capacity:
usize
, alloc: A) ->
Vec
<T, A>
🔬
This is a nightly-only experimental API. (
allocator_api
#32838
)
source
pub fn
with_capacity_in
(capacity:
usize
, alloc: A) ->
Vec
<T, A>
allocator_api
#32838
)
Constructs a new, empty
Vec<T, A>
with at least the specified capacity
with the provided allocator.
The vector will be able to hold at least
capacity
elements without
reallocating. This method is allowed to allocate for more elements than
capacity
. If
capacity
is 0, the vector will not allocate.
It is important to note that although the returned vector has the
minimum
capacity
specified, the vector will have a zero
length
. For
an explanation of the difference between length and capacity, see
Capacity and reallocation
.
If it is important to know the exact allocated capacity of a
Vec
,
always use the
capacity
method after construction.
For
Vec<T, A>
where
T
is a zero-sized type, there will be no allocation
and the capacity will always be
usize::MAX
.
Panics
Panics if the new capacity exceeds
isize::MAX
bytes.
Examples
#![feature(allocator_api)]
use std::alloc::System;
let mut vec = Vec::with_capacity_in(10, System);
// The vector contains no items, even though it has capacity for more
assert_eq!(vec.len(), 0);
assert_eq!(vec.capacity(), 10);
// These are all done without reallocating...
for i in 0..10 {
vec.push(i);
assert_eq!(vec.len(), 10);
assert_eq!(vec.capacity(), 10);
// ...but this may make the vector reallocate
vec.push(11);
assert_eq!(vec.len(), 11);
assert!(vec.capacity() >= 11);
// A vector of a zero-sized type will always over-allocate, since no
// allocation is necessary
let vec_units = Vec::<(), System>::with_capacity_in(10, System);
assert_eq!(vec_units.capacity(), usize::MAX);
Run
source
pub unsafe fn
from_raw_parts_in
(
ptr:
*mut T
,
length:
usize
,
capacity:
usize
,
alloc: A
) ->
Vec
<T, A>
🔬
This is a nightly-only experimental API. (
allocator_api
#32838
)
source
pub unsafe fn
from_raw_parts_in
(
ptr:
*mut T
,
length:
usize
,
capacity:
usize
,
alloc: A
) ->
Vec
<T, A>
allocator_api
#32838
)
Creates a
Vec<T, A>
directly from a pointer, a capacity, a length,
and an allocator.
Safety
This is highly unsafe, due to the number of invariants that aren’t
checked:
ptr
must be
currently allocated
via the given allocator
alloc
.
T
needs to have the same alignment as what
ptr
was allocated with.
(
T
having a less strict alignment is not sufficient, the alignment really
needs to be equal to satisfy the
dealloc
requirement that memory must be
allocated and deallocated with the same layout.)
The size of
T
times the
capacity
(ie. the allocated size in bytes) needs
to be the same size as the pointer was allocated with. (Because similar to
alignment,
dealloc
must be called with the same layout
size
.)
length
needs to be less than or equal to
capacity
.
The first
length
values must be properly initialized values of type
T
.
capacity
needs to
fit
the layout size that the pointer was allocated with.
The allocated size in bytes must be no larger than
isize::MAX
.
See the safety documentation of
pointer::offset
.
These requirements are always upheld by any
ptr
that has been allocated
via
Vec<T, A>
. Other allocation sources are allowed if the invariants are
upheld.
Violating these may cause problems like corrupting the allocator’s
internal data structures. For example it is
not
safe
to build a
Vec<u8>
from a pointer to a C
char
array with length
size_t
.
It’s also not safe to build one from a
Vec<u16>
and its length, because
the allocator cares about the alignment, and these two types have different
alignments. The buffer was allocated with alignment 2 (for
u16
), but after
turning it into a
Vec<u8>
it’ll be deallocated with alignment 1.
The ownership of
ptr
is effectively transferred to the
Vec<T>
which may then deallocate, reallocate or change the
contents of memory pointed to by the pointer at will. Ensure
that nothing else uses the pointer after calling this
function.
Examples
#![feature(allocator_api)]
use std::alloc::System;
use std::ptr;
use std::mem;
let mut v = Vec::with_capacity_in(3, System);
v.push(1);
v.push(2);
v.push(3);
// Prevent running `v`'s destructor so we are in complete control
// of the allocation.
let mut v = mem::ManuallyDrop::new(v);
// Pull out the various important pieces of information about `v`
let p = v.as_mut_ptr();
let len = v.len();
let cap = v.capacity();
let alloc = v.allocator();
unsafe {
// Overwrite memory with 4, 5, 6
for i in 0..len {
ptr::write(p.add(i), 4 + i);
// Put everything back together into a Vec
let rebuilt = Vec::from_raw_parts_in(p, len, cap, alloc.clone());
assert_eq!(rebuilt, [4, 5, 6]);
}
Run
Using memory that was allocated elsewhere:
use std::alloc::{alloc, Layout};
fn main() {
let layout = Layout::array::<u32>(16).expect("overflow cannot happen");
let vec = unsafe {
let mem = alloc(layout).cast::<u32>();
if mem.is_null() {
return;
mem.write(1_000_000);
Vec::from_raw_parts(mem, 1, 16)
assert_eq!(vec, &[1_000_000]);
assert_eq!(vec.capacity(), 16);
}
Run
source
pub fn
into_raw_parts
(self) -> (
*mut T
,
usize
,
usize
)
🔬
This is a nightly-only experimental API. (
vec_into_raw_parts
#65816
)
source
pub fn
into_raw_parts
(self) -> (
*mut T
,
usize
,
usize
)
vec_into_raw_parts
#65816
)
Decomposes a
Vec<T>
into its raw components.
Returns the raw pointer to the underlying data, the length of
the vector (in elements), and the allocated capacity of the
data (in elements). These are the same arguments in the same
order as the arguments to
from_raw_parts
.
After calling this function, the caller is responsible for the
memory previously managed by the
Vec
. The only way to do
this is to convert the raw pointer, length, and capacity back
into a
Vec
with the
from_raw_parts
function, allowing
the destructor to perform the cleanup.
Examples
#![feature(vec_into_raw_parts)]
let v: Vec<i32> = vec![-1, 0, 1];
let (ptr, len, cap) = v.into_raw_parts();
let rebuilt = unsafe {
// We can now make changes to the components, such as
// transmuting the raw pointer to a compatible type.
let ptr = ptr as *mut u32;
Vec::from_raw_parts(ptr, len, cap)
assert_eq!(rebuilt, [4294967295, 0, 1]);
Run
source
pub fn
into_raw_parts_with_alloc
(self) -> (
*mut T
,
usize
,
usize
, A)
🔬
This is a nightly-only experimental API. (
allocator_api
#32838
)
source
pub fn
into_raw_parts_with_alloc
(self) -> (
*mut T
,
usize
,
usize
, A)
allocator_api
#32838
)
Decomposes a
Vec<T>
into its raw components.
Returns the raw pointer to the underlying data, the length of the vector (in elements),
the allocated capacity of the data (in elements), and the allocator. These are the same
arguments in the same order as the arguments to
from_raw_parts_in
.
After calling this function, the caller is responsible for the
memory previously managed by the
Vec
. The only way to do
this is to convert the raw pointer, length, and capacity back
into a
Vec
with the
from_raw_parts_in
function, allowing
the destructor to perform the cleanup.
Examples
#![feature(allocator_api, vec_into_raw_parts)]
use std::alloc::System;
let mut v: Vec<i32, System> = Vec::new_in(System);
v.push(-1);
v.push(0);
v.push(1);
let (ptr, len, cap, alloc) = v.into_raw_parts_with_alloc();
let rebuilt = unsafe {
// We can now make changes to the components, such as
// transmuting the raw pointer to a compatible type.
let ptr = ptr as *mut u32;
Vec::from_raw_parts_in(ptr, len, cap, alloc)
assert_eq!(rebuilt, [4294967295, 0, 1]);
Run
source
pub fn
reserve
(&mut self, additional:
usize
)
source
pub fn
reserve
(&mut self, additional:
usize
)
Reserves capacity for at least
additional
more elements to be inserted
in the given
Vec<T>
. The collection may reserve more space to
speculatively avoid frequent reallocations. After calling
reserve
,
capacity will be greater than or equal to
self.len() + additional
.
Does nothing if capacity is already sufficient.
Panics
Panics if the new capacity exceeds
isize::MAX
bytes.
Examples
let mut vec = vec![1];
vec.reserve(10);
assert!(vec.capacity() >= 11);
Run
source
pub fn
reserve_exact
(&mut self, additional:
usize
)
source
pub fn
reserve_exact
(&mut self, additional:
usize
)
Reserves the minimum capacity for at least
additional
more elements to
be inserted in the given
Vec<T>
. Unlike
reserve
, this will not
deliberately over-allocate to speculatively avoid frequent allocations.
After calling
reserve_exact
, capacity will be greater than or equal to
self.len() + additional
. Does nothing if the capacity is already
sufficient.
Note that the allocator may give the collection more space than it
requests. Therefore, capacity can not be relied upon to be precisely
minimal. Prefer
reserve
if future insertions are expected.
Panics
Panics if the new capacity exceeds
isize::MAX
bytes.
Examples
let mut vec = vec![1];
vec.reserve_exact(10);
assert!(vec.capacity() >= 11);
Run
1.57.0
·
source
pub fn
try_reserve
(&mut self, additional:
usize
) ->
Result
<
()
,
TryReserveError
>
1.57.0
·
source
pub fn
try_reserve
(&mut self, additional:
usize
) ->
Result
<
()
,
TryReserveError
>
Tries to reserve capacity for at least
additional
more elements to be inserted
in the given
Vec<T>
. The collection may reserve more space to speculatively avoid
frequent reallocations. After calling
try_reserve
, capacity will be
greater than or equal to
self.len() + additional
if it returns
Ok(())
. Does nothing if capacity is already sufficient. This method
preserves the contents even if an error occurs.
Errors
If the capacity overflows, or the allocator reports a failure, then an error
is returned.
Examples
use std::collections::TryReserveError;
fn process_data(data: &[u32]) -> Result<Vec<u32>, TryReserveError> {
let mut output = Vec::new();
// Pre-reserve the memory, exiting if we can't
output.try_reserve(data.len())?;
// Now we know this can't OOM in the middle of our complex work
output.extend(data.iter().map(|&val| {
val * 2 + 5 // very complicated
Ok(output)
}
Run
1.57.0
·
source
pub fn
try_reserve_exact
(
&mut self,
additional:
usize
) ->
Result
<
()
,
TryReserveError
>
1.57.0
·
source
pub fn
try_reserve_exact
(
&mut self,
additional:
usize
) ->
Result
<
()
,
TryReserveError
>
Tries to reserve the minimum capacity for at least
additional
elements to be inserted in the given
Vec<T>
. Unlike
try_reserve
,
this will not deliberately over-allocate to speculatively avoid frequent
allocations. After calling
try_reserve_exact
, capacity will be greater
than or equal to
self.len() + additional
if it returns
Ok(())
.
Does nothing if the capacity is already sufficient.
Note that the allocator may give the collection more space than it
requests. Therefore, capacity can not be relied upon to be precisely
minimal. Prefer
try_reserve
if future insertions are expected.
Errors
If the capacity overflows, or the allocator reports a failure, then an error
is returned.
Examples
use std::collections::TryReserveError;
fn process_data(data: &[u32]) -> Result<Vec<u32>, TryReserveError> {
let mut output = Vec::new();
// Pre-reserve the memory, exiting if we can't
output.try_reserve_exact(data.len())?;
// Now we know this can't OOM in the middle of our complex work
output.extend(data.iter().map(|&val| {
val * 2 + 5 // very complicated
Ok(output)
}
Run
source
pub fn
shrink_to_fit
(&mut self)
source
pub fn
shrink_to_fit
(&mut self)
Shrinks the capacity of the vector as much as possible.
It will drop down as close as possible to the length but the allocator
may still inform the vector that there is space for a few more elements.
Examples
let mut vec = Vec::with_capacity(10);
vec.extend([1, 2, 3]);
assert_eq!(vec.capacity(), 10);
vec.shrink_to_fit();
assert!(vec.capacity() >= 3);
Run
1.56.0
·
source
pub fn
shrink_to
(&mut self, min_capacity:
usize
)
1.56.0
·
source
pub fn
shrink_to
(&mut self, min_capacity:
usize
)
Shrinks the capacity of the vector with a lower bound.
The capacity will remain at least as large as both the length
and the supplied value.
If the current capacity is less than the lower limit, this is a no-op.
Examples
let mut vec = Vec::with_capacity(10);
vec.extend([1, 2, 3]);
assert_eq!(vec.capacity(), 10);
vec.shrink_to(4);
assert!(vec.capacity() >= 4);
vec.shrink_to(0);
assert!(vec.capacity() >= 3);
Run
source
pub fn
into_boxed_slice
(self) ->
Box
<
[T]
, A>
source
pub fn
into_boxed_slice
(self) ->
Box
<
[T]
, A>
Converts the vector into
Box<[T]>
.
If the vector has excess capacity, its items will be moved into a
newly-allocated buffer with exactly the right capacity.
Examples
let v = vec![1, 2, 3];
let slice = v.into_boxed_slice();
Run
Any excess capacity is removed:
let mut vec = Vec::with_capacity(10);
vec.extend([1, 2, 3]);
assert_eq!(vec.capacity(), 10);
let slice = vec.into_boxed_slice();
assert_eq!(slice.into_vec().capacity(), 3);
Run
source
pub fn
truncate
(&mut self, len:
usize
)
source
pub fn
truncate
(&mut self, len:
usize
)
Shortens the vector, keeping the first
len
elements and dropping
the rest.
If
len
is greater than the vector’s current length, this has no
effect.
The
drain
method can emulate
truncate
, but causes the excess
elements to be returned instead of dropped.
Note that this method has no effect on the allocated capacity
of the vector.
Examples
Truncating a five element vector to two elements:
let mut vec = vec![1, 2, 3, 4, 5];
vec.truncate(2);
assert_eq!(vec, [1, 2]);
Run
No truncation occurs when
len
is greater than the vector’s current
length:
let mut vec = vec![1, 2, 3];
vec.truncate(8);
assert_eq!(vec, [1, 2, 3]);
Run
Truncating when
len == 0
is equivalent to calling the
clear
method.
let mut vec = vec![1, 2, 3];
vec.truncate(0);
assert_eq!(vec, []);
Run
1.7.0
·
source
pub fn
as_mut_slice
(&mut self) -> &mut
[T]
1.7.0
·
source
pub fn
as_mut_slice
(&mut self) -> &mut
[T]
1.37.0
·
source
pub fn
as_ptr
(&self) ->
*const T
1.37.0
·
source
pub fn
as_ptr
(&self) ->
*const T
Returns a raw pointer to the vector’s buffer, or a dangling raw pointer
valid for zero sized reads if the vector didn’t allocate.
The caller must ensure that the vector outlives the pointer this
function returns, or else it will end up pointing to garbage.
Modifying the vector may cause its buffer to be reallocated,
which would also make any pointers to it invalid.
The caller must also ensure that the memory the pointer (non-transitively) points to
is never written to (except inside an
UnsafeCell
) using this pointer or any pointer
derived from it. If you need to mutate the contents of the slice, use
as_mut_ptr
.
Examples
let x = vec![1, 2, 4];
let x_ptr = x.as_ptr();
unsafe {
for i in 0..x.len() {
assert_eq!(*x_ptr.add(i), 1 << i);
}
Run
1.37.0
·
source
pub fn
as_mut_ptr
(&mut self) ->
*mut T
1.37.0
·
source
pub fn
as_mut_ptr
(&mut self) ->
*mut T
Returns an unsafe mutable pointer to the vector’s buffer, or a dangling
raw pointer valid for zero sized reads if the vector didn’t allocate.
The caller must ensure that the vector outlives the pointer this
function returns, or else it will end up pointing to garbage.
Modifying the vector may cause its buffer to be reallocated,
which would also make any pointers to it invalid.
Examples
// Allocate vector big enough for 4 elements.
let size = 4;
let mut x: Vec<i32> = Vec::with_capacity(size);
let x_ptr = x.as_mut_ptr();
// Initialize elements via raw pointer writes, then set length.
unsafe {
for i in 0..size {
*x_ptr.add(i) = i as i32;
x.set_len(size);
assert_eq!(&*x, &[0, 1, 2, 3]);
Run
source
pub fn
allocator
(&self) ->
&A
🔬
This is a nightly-only experimental API. (
allocator_api
#32838
)
source
pub fn
allocator
(&self) ->
&A
allocator_api
#32838
)
Returns a reference to the underlying allocator.
source
pub unsafe fn
set_len
(&mut self, new_len:
usize
)
source
pub unsafe fn
set_len
(&mut self, new_len:
usize
)
Forces the length of the vector to
new_len
.
This is a low-level operation that maintains none of the normal
invariants of the type. Normally changing the length of a vector
is done using one of the safe operations instead, such as
truncate
,
resize
,
extend
, or
clear
.
Safety
new_len
must be less than or equal to
capacity()
.
The elements at
old_len..new_len
must be initialized.
Examples
This method can be useful for situations in which the vector
is serving as a buffer for other code, particularly over FFI:
pub fn get_dictionary(&self) -> Option<Vec<u8>> {
// Per the FFI method's docs, "32768 bytes is always enough".
let mut dict = Vec::with_capacity(32_768);
let mut dict_length = 0;
// SAFETY: When `deflateGetDictionary` returns `Z_OK`, it holds that:
// 1. `dict_length` elements were initialized.
// 2. `dict_length` <= the capacity (32_768)
// which makes `set_len` safe to call.
unsafe {
// Make the FFI call...
let r = deflateGetDictionary(self.strm, dict.as_mut_ptr(), &mut dict_length);
if r == Z_OK {
// ...and update the length to what was initialized.
dict.set_len(dict_length);
Some(dict)
} else {
}
Run
While the following example is sound, there is a memory leak since
the inner vectors were not freed prior to the
set_len
call:
let mut vec = vec![vec![1, 0, 0],
vec![0, 1, 0],
vec![0, 0, 1]];
// SAFETY:
// 1. `old_len..0` is empty so no elements need to be initialized.
// 2. `0 <= capacity` always holds whatever `capacity` is.
unsafe {
vec.set_len(0);
}
Run
Normally, here, one would use
clear
instead to correctly drop
the contents and thus not leak memory.
source
pub fn
swap_remove
(&mut self, index:
usize
) -> T
source
pub fn
swap_remove
(&mut self, index:
usize
) -> T
Removes an element from the vector and returns it.
The removed element is replaced by the last element of the vector.
This does not preserve ordering, but is
O
(1).
If you need to preserve the element order, use
remove
instead.
Panics
Panics if
index
is out of bounds.
Examples
let mut v = vec!["foo", "bar", "baz", "qux"];
assert_eq!(v.swap_remove(1), "bar");
assert_eq!(v, ["foo", "qux", "baz"]);
assert_eq!(v.swap_remove(0), "foo");
assert_eq!(v, ["baz", "qux"]);
Run
source
pub fn
remove
(&mut self, index:
usize
) -> T
source
pub fn
remove
(&mut self, index:
usize
) -> T
Removes and returns the element at position
index
within the vector,
shifting all elements after it to the left.
Note: Because this shifts over the remaining elements, it has a
worst-case performance of
O
(
n
). If you don’t need the order of elements
to be preserved, use
swap_remove
instead. If you’d like to remove
elements from the beginning of the
Vec
, consider using
VecDeque::pop_front
instead.
Panics
Panics if
index
is out of bounds.
Examples
let mut v = vec![1, 2, 3];
assert_eq!(v.remove(1), 2);
assert_eq!(v, [1, 3]);
Run
source
pub fn
retain
<F>(&mut self, f: F)
where
F:
FnMut
(
&T
) ->
bool
,
source
pub fn
retain
<F>(&mut self, f: F)
where
F:
FnMut
(
&T
) ->
bool
,
Retains only the elements specified by the predicate.
In other words, remove all elements
e
for which
f(&e)
returns
false
.
This method operates in place, visiting each element exactly once in the
original order, and preserves the order of the retained elements.
Examples
let mut vec = vec![1, 2, 3, 4];
vec.retain(|&x| x % 2 == 0);
assert_eq!(vec, [2, 4]);
Run
Because the elements are visited exactly once in the original order,
external state may be used to decide which elements to keep.
let mut vec = vec![1, 2, 3, 4, 5];
let keep = [false, true, true, false, true];
let mut iter = keep.iter();
vec.retain(|_| *iter.next().unwrap());
assert_eq!(vec, [2, 3, 5]);
Run
1.61.0
·
source
pub fn
retain_mut
<F>(&mut self, f: F)
where
F:
FnMut
(
&mut T
) ->
bool
,
1.61.0
·
source
pub fn
retain_mut
<F>(&mut self, f: F)
where
F:
FnMut
(
&mut T
) ->
bool
,
Retains only the elements specified by the predicate, passing a mutable reference to it.
In other words, remove all elements
e
such that
f(&mut e)
returns
false
.
This method operates in place, visiting each element exactly once in the
original order, and preserves the order of the retained elements.
Examples
let mut vec = vec![1, 2, 3, 4];
vec.retain_mut(|x| if *x <= 3 {
*x += 1;
} else {
false
assert_eq!(vec, [2, 3, 4]);
Run
1.16.0
·
source
pub fn
dedup_by_key
<F, K>(&mut self, key: F)
where
F:
FnMut
(
&mut T
) -> K,
K:
PartialEq
<K>,
1.16.0
·
source
pub fn
dedup_by_key
<F, K>(&mut self, key: F)
where
F:
FnMut
(
&mut T
) -> K,
K:
PartialEq
<K>,
1.16.0
·
source
pub fn
dedup_by
<F>(&mut self, same_bucket: F)
where
F:
FnMut
(
&mut T
,
&mut T
) ->
bool
,
1.16.0
·
source
pub fn
dedup_by
<F>(&mut self, same_bucket: F)
where
F:
FnMut
(
&mut T
,
&mut T
) ->
bool
,
Removes all but the first of consecutive elements in the vector satisfying a given equality
relation.
The
same_bucket
function is passed references to two elements from the vector and
must determine if the elements compare equal. The elements are passed in opposite order
from their order in the slice, so if
same_bucket(a, b)
returns
true
,
a
is removed.
If the vector is sorted, this removes all duplicates.
Examples
let mut vec = vec!["foo", "bar", "Bar", "baz", "bar"];
vec.dedup_by(|a, b| a.eq_ignore_ascii_case(b));
assert_eq!(vec, ["foo", "bar", "baz", "bar"]);
Run
source
pub fn
push_within_capacity
(&mut self, value: T) ->
Result
<
()
, T>
🔬
This is a nightly-only experimental API. (
vec_push_within_capacity
#100486
)
source
pub fn
push_within_capacity
(&mut self, value: T) ->
Result
<
()
, T>
vec_push_within_capacity
#100486
)
Appends an element if there is sufficient spare capacity, otherwise an error is returned
with the element.
Unlike
push
this method will not reallocate when there’s insufficient capacity.
The caller should use
reserve
or
try_reserve
to ensure that there is enough capacity.
Examples
A manual, panic-free alternative to
FromIterator
:
#![feature(vec_push_within_capacity)]
use std::collections::TryReserveError;
fn from_iter_fallible<T>(iter: impl Iterator<Item=T>) -> Result<Vec<T>, TryReserveError> {
let mut vec = Vec::new();
for value in iter {
if let Err(value) = vec.push_within_capacity(value) {
vec.try_reserve(1)?;
// this cannot fail, the previous line either returned or added at least 1 free slot
let _ = vec.push_within_capacity(value);
Ok(vec)
assert_eq!(from_iter_fallible(0..100), Ok(Vec::from_iter(0..100)));
Run
source
pub fn
pop
(&mut self) ->
Option
<T>
source
pub fn
pop
(&mut self) ->
Option
<T>
Removes the last element from a vector and returns it, or
None
if it
is empty.
If you’d like to pop the first element, consider using
VecDeque::pop_front
instead.
Examples
let mut vec = vec![1, 2, 3];
assert_eq!(vec.pop(), Some(3));
assert_eq!(vec, [1, 2]);
Run
1.6.0
·
source
pub fn
drain
<R>(&mut self, range: R) ->
Drain
<'_, T, A>
ⓘ
where
R:
RangeBounds
<
usize
>,
1.6.0
·
source
pub fn
drain
<R>(&mut self, range: R) ->
Drain
<'_, T, A>
ⓘ
where
R:
RangeBounds
<
usize
>,
Removes the specified range from the vector in bulk, returning all
removed elements as an iterator. If the iterator is dropped before
being fully consumed, it drops the remaining removed elements.
The returned iterator keeps a mutable borrow on the vector to optimize
its implementation.
Panics
Panics if the starting point is greater than the end point or if
the end point is greater than the length of the vector.
Leaking
If the returned iterator goes out of scope without being dropped (due to
mem::forget
, for example), the vector may have lost and leaked
elements arbitrarily, including elements outside the range.
Examples
let mut v = vec![1, 2, 3];
let u: Vec<_> = v.drain(1..).collect();
assert_eq!(v, &[1]);
assert_eq!(u, &[2, 3]);
// A full range clears the vector, like `clear()` does
v.drain(..);
assert_eq!(v, &[]);
Run
1.4.0
·
source
pub fn
split_off
(&mut self, at:
usize
) ->
Vec
<T, A>
where
A:
Clone
,
1.4.0
·
source
pub fn
split_off
(&mut self, at:
usize
) ->
Vec
<T, A>
where
A:
Clone
,
Splits the collection into two at the given index.
Returns a newly allocated vector containing the elements in the range
[at, len)
. After the call, the original vector will be left containing
the elements
[0, at)
with its previous capacity unchanged.
Panics
Panics if
at > len
.
Examples
let mut vec = vec![1, 2, 3];
let vec2 = vec.split_off(1);
assert_eq!(vec, [1]);
assert_eq!(vec2, [2, 3]);
Run
1.33.0
·
source
pub fn
resize_with
<F>(&mut self, new_len:
usize
, f: F)
where
F:
FnMut
() -> T,
1.33.0
·
source
pub fn
resize_with
<F>(&mut self, new_len:
usize
, f: F)
where
F:
FnMut
() -> T,
Resizes the
Vec
in-place so that
len
is equal to
new_len
.
If
new_len
is greater than
len
, the
Vec
is extended by the
difference, with each additional slot filled with the result of
calling the closure
f
. The return values from
f
will end up
in the
Vec
in the order they have been generated.
If
new_len
is less than
len
, the
Vec
is simply truncated.
This method uses a closure to create new values on every push. If
you’d rather
Clone
a given value, use
Vec::resize
. If you
want to use the
Default
trait to generate values, you can
pass
Default::default
as the second argument.
Examples
let mut vec = vec![1, 2, 3];
vec.resize_with(5, Default::default);
assert_eq!(vec, [1, 2, 3, 0, 0]);
let mut vec = vec![];
let mut p = 1;
vec.resize_with(4, || { p *= 2; p });
assert_eq!(vec, [2, 4, 8, 16]);
Run
1.47.0
·
source
pub fn
leak
<'a>(self) -> &'a mut
[T]
where
A: 'a,
1.47.0
·
source
pub fn
leak
<'a>(self) -> &'a mut
[T]
where
A: 'a,
Consumes and leaks the
Vec
, returning a mutable reference to the contents,
&'a mut [T]
. Note that the type
T
must outlive the chosen lifetime
'a
. If the type has only static references, or none at all, then this
may be chosen to be
'static
.
As of Rust 1.57, this method does not reallocate or shrink the
Vec
,
so the leaked allocation may include unused capacity that is not part
of the returned slice.
This function is mainly useful for data that lives for the remainder of
the program’s life. Dropping the returned reference will cause a memory
leak.
Examples
Simple usage:
let x = vec![1, 2, 3];
let static_ref: &'static mut [usize] = x.leak();
static_ref[0] += 1;
assert_eq!(static_ref, &[2, 2, 3]);
Run
1.60.0
·
source
pub fn
spare_capacity_mut
(&mut self) -> &mut [
MaybeUninit
<T>]
1.60.0
·
source
pub fn
spare_capacity_mut
(&mut self) -> &mut [
MaybeUninit
<T>]
Returns the remaining spare capacity of the vector as a slice of
MaybeUninit<T>
.
The returned slice can be used to fill the vector with data (e.g. by
reading from a file) before marking the data as initialized using the
set_len
method.
Examples
// Allocate vector big enough for 10 elements.
let mut v = Vec::with_capacity(10);
// Fill in the first 3 elements.
let uninit = v.spare_capacity_mut();
uninit[0].write(0);
uninit[1].write(1);
uninit[2].write(2);
// Mark the first 3 elements of the vector as being initialized.
unsafe {
v.set_len(3);
assert_eq!(&v, &[0, 1, 2]);
Run
source
pub fn
split_at_spare_mut
(&mut self) -> (&mut
[T]
, &mut [
MaybeUninit
<T>])
🔬
This is a nightly-only experimental API. (
vec_split_at_spare
#81944
)
source
pub fn
split_at_spare_mut
(&mut self) -> (&mut
[T]
, &mut [
MaybeUninit
<T>])
vec_split_at_spare
#81944
)
Returns vector content as a slice of
T
, along with the remaining spare
capacity of the vector as a slice of
MaybeUninit<T>
.
The returned spare capacity slice can be used to fill the vector with data
(e.g. by reading from a file) before marking the data as initialized using
the
set_len
method.
Note that this is a low-level API, which should be used with care for
optimization purposes. If you need to append data to a
Vec
you can use
push
,
extend
,
extend_from_slice
,
extend_from_within
,
insert
,
append
,
resize
or
resize_with
, depending on your exact needs.
Examples
#![feature(vec_split_at_spare)]
let mut v = vec![1, 1, 2];
// Reserve additional space big enough for 10 elements.
v.reserve(10);
let (init, uninit) = v.split_at_spare_mut();
let sum = init.iter().copied().sum::<u32>();
// Fill in the next 4 elements.
uninit[0].write(sum);
uninit[1].write(sum * 2);
uninit[2].write(sum * 3);
uninit[3].write(sum * 4);
// Mark the 4 elements of the vector as being initialized.
unsafe {
let len = v.len();
v.set_len(len + 4);
assert_eq!(&v, &[1, 1, 2, 4, 8, 12, 16]);
Run
source
§
impl<T, A>
Vec
<T, A>
where
T:
Clone
,
A:
Allocator
,
source
§
impl<T, A>
Vec
<T, A>
where
T:
Clone
,
A:
Allocator
,
1.5.0
·
source
pub fn
resize
(&mut self, new_len:
usize
, value: T)
1.5.0
·
source
pub fn
resize
(&mut self, new_len:
usize
, value: T)
Resizes the
Vec
in-place so that
len
is equal to
new_len
.
If
new_len
is greater than
len
, the
Vec
is extended by the
difference, with each additional slot filled with
value
.
If
new_len
is less than
len
, the
Vec
is simply truncated.
This method requires
T
to implement
Clone
,
in order to be able to clone the passed value.
If you need more flexibility (or want to rely on
Default
instead of
Clone
), use
Vec::resize_with
.
If you only need to resize to a smaller size, use
Vec::truncate
.
Examples
let mut vec = vec!["hello"];
vec.resize(3, "world");
assert_eq!(vec, ["hello", "world", "world"]);
let mut vec = vec![1, 2, 3, 4];
vec.resize(2, 0);
assert_eq!(vec, [1, 2]);
Run
1.6.0
·
source
pub fn
extend_from_slice
(&mut self, other: &
[T]
)
1.6.0
·
source
pub fn
extend_from_slice
(&mut self, other: &
[T]
)
Clones and appends all elements in a slice to the
Vec
.
Iterates over the slice
other
, clones each element, and then appends
it to this
Vec
. The
other
slice is traversed in-order.
Note that this function is same as
extend
except that it is
specialized to work with slices instead. If and when Rust gets
specialization this function will likely be deprecated (but still
available).
Examples
let mut vec = vec![1];
vec.extend_from_slice(&[2, 3, 4]);
assert_eq!(vec, [1, 2, 3, 4]);
Run
1.53.0
·
source
pub fn
extend_from_within
<R>(&mut self, src: R)
where
R:
RangeBounds
<
usize
>,
1.53.0
·
source
pub fn
extend_from_within
<R>(&mut self, src: R)
where
R:
RangeBounds
<
usize
>,
Copies elements from
src
range to the end of the vector.
Panics
Panics if the starting point is greater than the end point or if
the end point is greater than the length of the vector.
Examples
let mut vec = vec![0, 1, 2, 3, 4];
vec.extend_from_within(2..);
assert_eq!(vec, [0, 1, 2, 3, 4, 2, 3, 4]);
vec.extend_from_within(..2);
assert_eq!(vec, [0, 1, 2, 3, 4, 2, 3, 4, 0, 1]);
vec.extend_from_within(4..8);
assert_eq!(vec, [0, 1, 2, 3, 4, 2, 3, 4, 0, 1, 4, 2, 3, 4]);
Run
source
§
impl<T, A, const N:
usize
>
Vec
<
[T; N]
, A>
where
A:
Allocator
,
source
§
impl<T, A, const N:
usize
>
Vec
<
[T; N]
, A>
where
A:
Allocator
,
source
pub fn
into_flattened
(self) ->
Vec
<T, A>
🔬
This is a nightly-only experimental API. (
slice_flatten
#95629
)
source
pub fn
into_flattened
(self) ->
Vec
<T, A>
slice_flatten
#95629
)
Takes a
Vec<[T; N]>
and flattens it into a
Vec<T>
.
Panics
Panics if the length of the resulting vector would overflow a
usize
.
This is only possible when flattening a vector of arrays of zero-sized
types, and thus tends to be irrelevant in practice. If
size_of::<T>() > 0
, this will never panic.
Examples
#![feature(slice_flatten)]
let mut vec = vec![[1, 2, 3], [4, 5, 6], [7, 8, 9]];
assert_eq!(vec.pop(), Some([7, 8, 9]));
let mut flattened = vec.into_flattened();
assert_eq!(flattened.pop(), Some(6));
Run
source
§
impl<T, A>
Vec
<T, A>
where
A:
Allocator
,
source
§
impl<T, A>
Vec
<T, A>
where
A:
Allocator
,
1.21.0
·
source
pub fn
splice
<R, I>(
&mut self,
range: R,
replace_with: I
) ->
Splice
<'_, <I as
IntoIterator
>::
IntoIter
, A>
ⓘ
where
R:
RangeBounds
<
usize
>,
I:
IntoIterator
<Item = T>,
1.21.0
·
source
pub fn
splice
<R, I>(
&mut self,
range: R,
replace_with: I
) ->
Splice
<'_, <I as
IntoIterator
>::
IntoIter
, A>
ⓘ
where
R:
RangeBounds
<
usize
>,
I:
IntoIterator
<Item = T>,
Creates a splicing iterator that replaces the specified range in the vector
with the given
replace_with
iterator and yields the removed items.
replace_with
does not need to be the same length as
range
.
range
is removed even if the iterator is not consumed until the end.
It is unspecified how many elements are removed from the vector
if the
Splice
value is leaked.
The input iterator
replace_with
is only consumed when the
Splice
value is dropped.
This is optimal if:
The tail (elements in the vector after
range
) is empty,
or
replace_with
yields fewer or equal elements than
range
’s length
or the lower bound of its
size_hint()
is exact.
Otherwise, a temporary vector is allocated and the tail is moved twice.
Panics
Panics if the starting point is greater than the end point or if
the end point is greater than the length of the vector.
Examples
let mut v = vec![1, 2, 3, 4];
let new = [7, 8, 9];
let u: Vec<_> = v.splice(1..3, new).collect();
assert_eq!(v, &[1, 7, 8, 9, 4]);
assert_eq!(u, &[2, 3]);
Run
source
pub fn
drain_filter
<F>(&mut self, filter: F) ->
DrainFilter
<'_, T, F, A>
ⓘ
where
F:
FnMut
(
&mut T
) ->
bool
,
🔬
This is a nightly-only experimental API. (
drain_filter
#43244
)
source
pub fn
drain_filter
<F>(&mut self, filter: F) ->
DrainFilter
<'_, T, F, A>
ⓘ
where
F:
FnMut
(
&mut T
) ->
bool
,
drain_filter
#43244
)
Creates an iterator which uses a closure to determine if an element should be removed.
If the closure returns true, then the element is removed and yielded.
If the closure returns false, the element will remain in the vector and will not be yielded
by the iterator.
Using this method is equivalent to the following code:
let mut i = 0;
while i < vec.len() {
if some_predicate(&mut vec[i]) {
let val = vec.remove(i);
// your code here
} else {
i += 1;
But drain_filter
is easier to use. drain_filter
is also more efficient,
because it can backshift the elements of the array in bulk.
Note that drain_filter
also lets you mutate every element in the filter closure,
regardless of whether you choose to keep or remove it.
Examples
Splitting an array into evens and odds, reusing the original allocation:
#![feature(drain_filter)]
let mut numbers = vec![1, 2, 3, 4, 5, 6, 8, 9, 11, 13, 14, 15];
let evens = numbers.drain_filter(|x| *x % 2 == 0).collect::<Vec<_>>();
let odds = numbers;
assert_eq!(evens, vec![2, 4, 6, 8, 14]);
assert_eq!(odds, vec![1, 3, 5, 9, 11, 13, 15]);
Run
Methods from
Deref
<Target =
[T]
>
§
Methods from
Deref
<Target =
[T]
>
§
source
pub fn
sort_floats
(&mut self)
🔬
This is a nightly-only experimental API. (
sort_floats
#93396
)
source
pub fn
sort_floats
(&mut self)
🔬
This is a nightly-only experimental API. (
sort_floats
#93396
)
Sorts the slice of floats.
This sort is in-place (i.e. does not allocate),
O
(
n
* log(
n
)) worst-case, and uses
the ordering defined by
f32::total_cmp
.
Current implementation
This uses the same sorting algorithm as
sort_unstable_by
.
Examples
#![feature(sort_floats)]
let mut v = [2.6, -5e-8, f32::NAN, 8.29, f32::INFINITY, -1.0, 0.0, -f32::INFINITY, -0.0];
v.sort_floats();
let sorted = [-f32::INFINITY, -1.0, -5e-8, -0.0, 0.0, 2.6, 8.29, f32::INFINITY, f32::NAN];
assert_eq!(&v[..8], &sorted[..8]);
assert!(v[8].is_nan());
Run
source
pub fn
sort_floats
(&mut self)
🔬
This is a nightly-only experimental API. (
sort_floats
#93396
)
source
pub fn
sort_floats
(&mut self)
🔬
This is a nightly-only experimental API. (
sort_floats
#93396
)
Sorts the slice of floats.
This sort is in-place (i.e. does not allocate),
O
(
n
* log(
n
)) worst-case, and uses
the ordering defined by
f64::total_cmp
.
Current implementation
This uses the same sorting algorithm as
sort_unstable_by
.
Examples
#![feature(sort_floats)]
let mut v = [2.6, -5e-8, f64::NAN, 8.29, f64::INFINITY, -1.0, 0.0, -f64::INFINITY, -0.0];
v.sort_floats();
let sorted = [-f64::INFINITY, -1.0, -5e-8, -0.0, 0.0, 2.6, 8.29, f64::INFINITY, f64::NAN];
assert_eq!(&v[..8], &sorted[..8]);
assert!(v[8].is_nan());
Run
1.23.0
·
source
pub fn
is_ascii
(&self) ->
bool
1.23.0
·
source
pub fn
is_ascii
(&self) ->
bool
Checks if all bytes in this slice are within the ASCII range.
1.23.0
·
source
pub fn
eq_ignore_ascii_case
(&self, other: &[
u8
]) ->
bool
1.23.0
·
source
pub fn
eq_ignore_ascii_case
(&self, other: &[
u8
]) ->
bool
Checks that two slices are an ASCII case-insensitive match.
Same as
to_ascii_lowercase(a) == to_ascii_lowercase(b)
,
but without allocating and copying temporaries.
1.23.0
·
source
pub fn
make_ascii_uppercase
(&mut self)
1.23.0
·
source
pub fn
make_ascii_uppercase
(&mut self)
Converts this slice to its ASCII upper case equivalent in-place.
ASCII letters ‘a’ to ‘z’ are mapped to ‘A’ to ‘Z’,
but non-ASCII letters are unchanged.
To return a new uppercased value without modifying the existing one, use
to_ascii_uppercase
.
1.23.0
·
source
pub fn
make_ascii_lowercase
(&mut self)
1.23.0
·
source
pub fn
make_ascii_lowercase
(&mut self)
Converts this slice to its ASCII lower case equivalent in-place.
ASCII letters ‘A’ to ‘Z’ are mapped to ‘a’ to ‘z’,
but non-ASCII letters are unchanged.
To return a new lowercased value without modifying the existing one, use
to_ascii_lowercase
.
1.60.0
·
source
pub fn
escape_ascii
(&self) ->
EscapeAscii
<'_>
ⓘ
1.60.0
·
source
pub fn
escape_ascii
(&self) ->
EscapeAscii
<'_>
ⓘ
Returns an iterator that produces an escaped version of this slice,
treating it as an ASCII string.
Examples
let
s =
b"0\t\r\n'\"\\\x9d"
;
let
escaped = s.escape_ascii().to_string();
assert_eq!
(escaped,
"0\\t\\r\\n\\'\\\"\\\\\\x9d"
);
Run
source
pub fn
trim_ascii_start
(&self) -> &[
u8
]
ⓘ
🔬
This is a nightly-only experimental API. (
byte_slice_trim_ascii
#94035
)
source
pub fn
trim_ascii_start
(&self) -> &[
u8
]
ⓘ
byte_slice_trim_ascii
#94035
)
Returns a byte slice with leading ASCII whitespace bytes removed.
‘Whitespace’ refers to the definition used by
u8::is_ascii_whitespace
.
Examples
#![feature(byte_slice_trim_ascii)]
assert_eq!(b" \t hello world\n".trim_ascii_start(), b"hello world\n");
assert_eq!(b" ".trim_ascii_start(), b"");
assert_eq!(b"".trim_ascii_start(), b"");
Run
source
pub fn
trim_ascii_end
(&self) -> &[
u8
]
ⓘ
🔬
This is a nightly-only experimental API. (
byte_slice_trim_ascii
#94035
)
source
pub fn
trim_ascii_end
(&self) -> &[
u8
]
ⓘ
byte_slice_trim_ascii
#94035
)
Returns a byte slice with trailing ASCII whitespace bytes removed.
‘Whitespace’ refers to the definition used by
u8::is_ascii_whitespace
.
Examples
#![feature(byte_slice_trim_ascii)]
assert_eq!(b"\r hello world\n ".trim_ascii_end(), b"\r hello world");
assert_eq!(b" ".trim_ascii_end(), b"");
assert_eq!(b"".trim_ascii_end(), b"");
Run
source
pub fn
trim_ascii
(&self) -> &[
u8
]
ⓘ
🔬
This is a nightly-only experimental API. (
byte_slice_trim_ascii
#94035
)
source
pub fn
trim_ascii
(&self) -> &[
u8
]
ⓘ
byte_slice_trim_ascii
#94035
)
Returns a byte slice with leading and trailing ASCII whitespace bytes
removed.
‘Whitespace’ refers to the definition used by
u8::is_ascii_whitespace
.
Examples
#![feature(byte_slice_trim_ascii)]
assert_eq!(b"\r hello world\n ".trim_ascii(), b"hello world");
assert_eq!(b" ".trim_ascii(), b"");
assert_eq!(b"".trim_ascii(), b"");
Run
1.5.0
·
source
pub fn
split_first
(&self) ->
Option
<(
&T
, &
[T]
)>
1.5.0
·
source
pub fn
split_first
(&self) ->
Option
<(
&T
, &
[T]
)>
1.5.0
·
source
pub fn
split_first_mut
(&mut self) ->
Option
<(
&mut T
, &mut
[T]
)>
1.5.0
·
source
pub fn
split_first_mut
(&mut self) ->
Option
<(
&mut T
, &mut
[T]
)>
1.5.0
·
source
pub fn
split_last
(&self) ->
Option
<(
&T
, &
[T]
)>
1.5.0
·
source
pub fn
split_last
(&self) ->
Option
<(
&T
, &
[T]
)>
1.5.0
·
source
pub fn
split_last_mut
(&mut self) ->
Option
<(
&mut T
, &mut
[T]
)>
1.5.0
·
source
pub fn
split_last_mut
(&mut self) ->
Option
<(
&mut T
, &mut
[T]
)>
source
pub fn
get
<I>(&self, index: I) ->
Option
<&<I as
SliceIndex
<
[T]
>>::
Output
>
where
I:
SliceIndex
<
[T]
>,
source
pub fn
get
<I>(&self, index: I) ->
Option
<&<I as
SliceIndex
<
[T]
>>::
Output
>
where
I:
SliceIndex
<
[T]
>,
Returns a reference to an element or subslice depending on the type of
index.
If given a position, returns a reference to the element at that
position or
None
if out of bounds.
If given a range, returns the subslice corresponding to that range,
or
None
if out of bounds.
Examples
let v = [10, 40, 30];
assert_eq!(Some(&40), v.get(1));
assert_eq!(Some(&[10, 40][..]), v.get(0..2));
assert_eq!(None, v.get(3));
assert_eq!(None, v.get(0..4));
Run
source
pub fn
get_mut
<I>(
&mut self,
index: I
) ->
Option
<&mut <I as
SliceIndex
<
[T]
>>::
Output
>
where
I:
SliceIndex
<
[T]
>,
source
pub fn
get_mut
<I>(
&mut self,
index: I
) ->
Option
<&mut <I as
SliceIndex
<
[T]
>>::
Output
>
where
I:
SliceIndex
<
[T]
>,
source
pub unsafe fn
get_unchecked
<I>(
&self,
index: I
) -> &<I as
SliceIndex
<
[T]
>>::
Output
where
I:
SliceIndex
<
[T]
>,
source
pub unsafe fn
get_unchecked
<I>(
&self,
index: I
) -> &<I as
SliceIndex
<
[T]
>>::
Output
where
I:
SliceIndex
<
[T]
>,
Returns a reference to an element or subslice, without doing bounds
checking.
For a safe alternative see
get
.
Safety
Calling this method with an out-of-bounds index is
undefined behavior
even if the resulting reference is not used.
Examples
let x = &[1, 2, 4];
unsafe {
assert_eq!(x.get_unchecked(1), &2);
}
Run
source
pub unsafe fn
get_unchecked_mut
<I>(
&mut self,
index: I
) -> &mut <I as
SliceIndex
<
[T]
>>::
Output
where
I:
SliceIndex
<
[T]
>,
source
pub unsafe fn
get_unchecked_mut
<I>(
&mut self,
index: I
) -> &mut <I as
SliceIndex
<
[T]
>>::
Output
where
I:
SliceIndex
<
[T]
>,
Returns a mutable reference to an element or subslice, without doing
bounds checking.
For a safe alternative see
get_mut
.
Safety
Calling this method with an out-of-bounds index is
undefined behavior
even if the resulting reference is not used.
Examples
let x = &mut [1, 2, 4];
unsafe {
let elem = x.get_unchecked_mut(1);
*elem = 13;
assert_eq!(x, &[1, 13, 4]);
Run
source
pub fn
as_ptr
(&self) ->
*const T
source
pub fn
as_ptr
(&self) ->
*const T
Returns a raw pointer to the slice’s buffer.
The caller must ensure that the slice outlives the pointer this
function returns, or else it will end up pointing to garbage.
The caller must also ensure that the memory the pointer (non-transitively) points to
is never written to (except inside an
UnsafeCell
) using this pointer or any pointer
derived from it. If you need to mutate the contents of the slice, use
as_mut_ptr
.
Modifying the container referenced by this slice may cause its buffer
to be reallocated, which would also make any pointers to it invalid.
Examples
let x = &[1, 2, 4];
let x_ptr = x.as_ptr();
unsafe {
for i in 0..x.len() {
assert_eq!(x.get_unchecked(i), &*x_ptr.add(i));
}
Run
source
pub fn
as_mut_ptr
(&mut self) ->
*mut T
source
pub fn
as_mut_ptr
(&mut self) ->
*mut T
Returns an unsafe mutable pointer to the slice’s buffer.
The caller must ensure that the slice outlives the pointer this
function returns, or else it will end up pointing to garbage.
Modifying the container referenced by this slice may cause its buffer
to be reallocated, which would also make any pointers to it invalid.
Examples
let x = &mut [1, 2, 4];
let x_ptr = x.as_mut_ptr();
unsafe {
for i in 0..x.len() {
*x_ptr.add(i) += 2;
assert_eq!(x, &[3, 4, 6]);
Run
1.48.0
·
source
pub fn
as_ptr_range
(&self) ->
Range
<
*const T
>
ⓘ
1.48.0
·
source
pub fn
as_ptr_range
(&self) ->
Range
<
*const T
>
ⓘ
Returns the two raw pointers spanning the slice.
The returned range is half-open, which means that the end pointer
points
one past
the last element of the slice. This way, an empty
slice is represented by two equal pointers, and the difference between
the two pointers represents the size of the slice.
See
as_ptr
for warnings on using these pointers. The end pointer
requires extra caution, as it does not point to a valid element in the
slice.
This function is useful for interacting with foreign interfaces which
use two pointers to refer to a range of elements in memory, as is
common in C++.
It can also be useful to check if a pointer to an element refers to an
element of this slice:
let a = [1, 2, 3];
let x = &a[1] as *const _;
let y = &5 as *const _;
assert!(a.as_ptr_range().contains(&x));
assert!(!a.as_ptr_range().contains(&y));
Run
1.48.0
·
source
pub fn
as_mut_ptr_range
(&mut self) ->
Range
<
*mut T
>
ⓘ
1.48.0
·
source
pub fn
as_mut_ptr_range
(&mut self) ->
Range
<
*mut T
>
ⓘ
Returns the two unsafe mutable pointers spanning the slice.
The returned range is half-open, which means that the end pointer
points
one past
the last element of the slice. This way, an empty
slice is represented by two equal pointers, and the difference between
the two pointers represents the size of the slice.
See
as_mut_ptr
for warnings on using these pointers. The end
pointer requires extra caution, as it does not point to a valid element
in the slice.
This function is useful for interacting with foreign interfaces which
use two pointers to refer to a range of elements in memory, as is
common in C++.
source
pub unsafe fn
swap_unchecked
(&mut self, a:
usize
, b:
usize
)
🔬
This is a nightly-only experimental API. (
slice_swap_unchecked
#88539
)
source
pub unsafe fn
swap_unchecked
(&mut self, a:
usize
, b:
usize
)
slice_swap_unchecked
#88539
)
Swaps two elements in the slice, without doing bounds checking.
For a safe alternative see
swap
.
Arguments
a - The index of the first element
b - The index of the second element
Safety
Calling this method with an out-of-bounds index is
undefined behavior
.
The caller has to ensure that
a < self.len()
and
b < self.len()
.
Examples
#![feature(slice_swap_unchecked)]
let mut v = ["a", "b", "c", "d"];
// SAFETY: we know that 1 and 3 are both indices of the slice
unsafe { v.swap_unchecked(1, 3) };
assert!(v == ["a", "d", "c", "b"]);
Run
source
pub fn
windows
(&self, size:
usize
) ->
Windows
<'_, T>
ⓘ
source
pub fn
windows
(&self, size:
usize
) ->
Windows
<'_, T>
ⓘ
Returns an iterator over all contiguous windows of length
size
. The windows overlap. If the slice is shorter than
size
, the iterator returns no values.
Panics
Panics if
size
is 0.
Examples
let slice = ['r', 'u', 's', 't'];
let mut iter = slice.windows(2);
assert_eq!(iter.next().unwrap(), &['r', 'u']);
assert_eq!(iter.next().unwrap(), &['u', 's']);
assert_eq!(iter.next().unwrap(), &['s', 't']);
assert!(iter.next().is_none());
Run
If the slice is shorter than
size
:
let slice = ['f', 'o', 'o'];
let mut iter = slice.windows(4);
assert!(iter.next().is_none());
Run
There’s no
windows_mut
, as that existing would let safe code violate the
“only one
&mut
at a time to the same thing” rule. However, you can sometimes
use
Cell::as_slice_of_cells
in
conjunction with
windows
to accomplish something similar:
use std::cell::Cell;
let mut array = ['R', 'u', 's', 't', ' ', '2', '0', '1', '5'];
let slice = &mut array[..];
let slice_of_cells: &[Cell<char>] = Cell::from_mut(slice).as_slice_of_cells();
for w in slice_of_cells.windows(3) {
Cell::swap(&w[0], &w[2]);
assert_eq!(array, ['s', 't', ' ', '2', '0', '1', '5', 'u', 'R']);
Run
source
pub fn
chunks
(&self, chunk_size:
usize
) ->
Chunks
<'_, T>
ⓘ
source
pub fn
chunks
(&self, chunk_size:
usize
) ->
Chunks
<'_, T>
ⓘ
Returns an iterator over
chunk_size
elements of the slice at a time, starting at the
beginning of the slice.
The chunks are slices and do not overlap. If
chunk_size
does not divide the length of the
slice, then the last chunk will not have length
chunk_size
.
See
chunks_exact
for a variant of this iterator that returns chunks of always exactly
chunk_size
elements, and
rchunks
for the same iterator but starting at the end of the
slice.
Panics
Panics if
chunk_size
is 0.
Examples
let slice = ['l', 'o', 'r', 'e', 'm'];
let mut iter = slice.chunks(2);
assert_eq!(iter.next().unwrap(), &['l', 'o']);
assert_eq!(iter.next().unwrap(), &['r', 'e']);
assert_eq!(iter.next().unwrap(), &['m']);
assert!(iter.next().is_none());
Run
source
pub fn
chunks_mut
(&mut self, chunk_size:
usize
) ->
ChunksMut
<'_, T>
ⓘ
source
pub fn
chunks_mut
(&mut self, chunk_size:
usize
) ->
ChunksMut
<'_, T>
ⓘ
Returns an iterator over
chunk_size
elements of the slice at a time, starting at the
beginning of the slice.
The chunks are mutable slices, and do not overlap. If
chunk_size
does not divide the
length of the slice, then the last chunk will not have length
chunk_size
.
See
chunks_exact_mut
for a variant of this iterator that returns chunks of always
exactly
chunk_size
elements, and
rchunks_mut
for the same iterator but starting at
the end of the slice.
Panics
Panics if
chunk_size
is 0.
Examples
let v = &mut [0, 0, 0, 0, 0];
let mut count = 1;
for chunk in v.chunks_mut(2) {
for elem in chunk.iter_mut() {
*elem += count;
count += 1;
assert_eq!(v, &[1, 1, 2, 2, 3]);
Run
1.31.0
·
source
pub fn
chunks_exact
(&self, chunk_size:
usize
) ->
ChunksExact
<'_, T>
ⓘ
1.31.0
·
source
pub fn
chunks_exact
(&self, chunk_size:
usize
) ->
ChunksExact
<'_, T>
ⓘ
Returns an iterator over
chunk_size
elements of the slice at a time, starting at the
beginning of the slice.
The chunks are slices and do not overlap. If
chunk_size
does not divide the length of the
slice, then the last up to
chunk_size-1
elements will be omitted and can be retrieved
from the
remainder
function of the iterator.
Due to each chunk having exactly
chunk_size
elements, the compiler can often optimize the
resulting code better than in the case of
chunks
.
See
chunks
for a variant of this iterator that also returns the remainder as a smaller
chunk, and
rchunks_exact
for the same iterator but starting at the end of the slice.
Panics
Panics if
chunk_size
is 0.
Examples
let slice = ['l', 'o', 'r', 'e', 'm'];
let mut iter = slice.chunks_exact(2);
assert_eq!(iter.next().unwrap(), &['l', 'o']);
assert_eq!(iter.next().unwrap(), &['r', 'e']);
assert!(iter.next().is_none());
assert_eq!(iter.remainder(), &['m']);
Run
1.31.0
·
source
pub fn
chunks_exact_mut
(&mut self, chunk_size:
usize
) ->
ChunksExactMut
<'_, T>
ⓘ
1.31.0
·
source
pub fn
chunks_exact_mut
(&mut self, chunk_size:
usize
) ->
ChunksExactMut
<'_, T>
ⓘ
Returns an iterator over
chunk_size
elements of the slice at a time, starting at the
beginning of the slice.
The chunks are mutable slices, and do not overlap. If
chunk_size
does not divide the
length of the slice, then the last up to
chunk_size-1
elements will be omitted and can be
retrieved from the
into_remainder
function of the iterator.
Due to each chunk having exactly
chunk_size
elements, the compiler can often optimize the
resulting code better than in the case of
chunks_mut
.
See
chunks_mut
for a variant of this iterator that also returns the remainder as a
smaller chunk, and
rchunks_exact_mut
for the same iterator but starting at the end of
the slice.
Panics
Panics if
chunk_size
is 0.
Examples
let v = &mut [0, 0, 0, 0, 0];
let mut count = 1;
for chunk in v.chunks_exact_mut(2) {
for elem in chunk.iter_mut() {
*elem += count;
count += 1;
assert_eq!(v, &[1, 1, 2, 2, 0]);
Run
source
pub unsafe fn
as_chunks_unchecked
<const N:
usize
>(&self) -> &[
[T; N]
]
🔬
This is a nightly-only experimental API. (
slice_as_chunks
#74985
)
source
pub unsafe fn
as_chunks_unchecked
<const N:
usize
>(&self) -> &[
[T; N]
]
slice_as_chunks
#74985
)
Splits the slice into a slice of
N
-element arrays,
assuming that there’s no remainder.
Safety
This may only be called when
The slice splits exactly into
N
-element chunks (aka
self.len() % N == 0
).
N != 0
.
Examples
#![feature(slice_as_chunks)]
let slice: &[char] = &['l', 'o', 'r', 'e', 'm', '!'];
let chunks: &[[char; 1]] =
// SAFETY: 1-element chunks never have remainder
unsafe { slice.as_chunks_unchecked() };
assert_eq!(chunks, &[['l'], ['o'], ['r'], ['e'], ['m'], ['!']]);
let chunks: &[[char; 3]] =
// SAFETY: The slice length (6) is a multiple of 3
unsafe { slice.as_chunks_unchecked() };
assert_eq!(chunks, &[['l', 'o', 'r'], ['e', 'm', '!']]);
// These would be unsound:
// let chunks: &[[_; 5]] = slice.as_chunks_unchecked() // The slice length is not a multiple of 5
// let chunks: &[[_; 0]] = slice.as_chunks_unchecked() // Zero-length chunks are never allowed
Run
source
pub fn
as_chunks
<const N:
usize
>(&self) -> (&[
[T; N]
], &
[T]
)
🔬
This is a nightly-only experimental API. (
slice_as_chunks
#74985
)
source
pub fn
as_chunks
<const N:
usize
>(&self) -> (&[
[T; N]
], &
[T]
)
slice_as_chunks
#74985
)
Splits the slice into a slice of
N
-element arrays,
starting at the beginning of the slice,
and a remainder slice with length strictly less than
N
.
Panics
Panics if
N
is 0. This check will most probably get changed to a compile time
error before this method gets stabilized.
Examples
#![feature(slice_as_chunks)]
let slice = ['l', 'o', 'r', 'e', 'm'];
let (chunks, remainder) = slice.as_chunks();
assert_eq!(chunks, &[['l', 'o'], ['r', 'e']]);
assert_eq!(remainder, &['m']);
Run
If you expect the slice to be an exact multiple, you can combine
let
-
else
with an empty slice pattern:
#![feature(slice_as_chunks)]
let slice = ['R', 'u', 's', 't'];
let (chunks, []) = slice.as_chunks::<2>() else {
panic!("slice didn't have even length")
assert_eq!(chunks, &[['R', 'u'], ['s', 't']]);
Run
source
pub fn
as_rchunks
<const N:
usize
>(&self) -> (&
[T]
, &[
[T; N]
])
🔬
This is a nightly-only experimental API. (
slice_as_chunks
#74985
)
source
pub fn
as_rchunks
<const N:
usize
>(&self) -> (&
[T]
, &[
[T; N]
])
slice_as_chunks
#74985
)
Splits the slice into a slice of
N
-element arrays,
starting at the end of the slice,
and a remainder slice with length strictly less than
N
.
Panics
Panics if
N
is 0. This check will most probably get changed to a compile time
error before this method gets stabilized.
Examples
#![feature(slice_as_chunks)]
let slice = ['l', 'o', 'r', 'e', 'm'];
let (remainder, chunks) = slice.as_rchunks();
assert_eq!(remainder, &['l']);
assert_eq!(chunks, &[['o', 'r'], ['e', 'm']]);
Run
source
pub fn
array_chunks
<const N:
usize
>(&self) ->
ArrayChunks
<'_, T, N>
ⓘ
🔬
This is a nightly-only experimental API. (
array_chunks
#74985
)
source
pub fn
array_chunks
<const N:
usize
>(&self) ->
ArrayChunks
<'_, T, N>
ⓘ
array_chunks
#74985
)
Returns an iterator over
N
elements of the slice at a time, starting at the
beginning of the slice.
The chunks are array references and do not overlap. If
N
does not divide the
length of the slice, then the last up to
N-1
elements will be omitted and can be
retrieved from the
remainder
function of the iterator.
This method is the const generic equivalent of
chunks_exact
.
Panics
Panics if
N
is 0. This check will most probably get changed to a compile time
error before this method gets stabilized.
Examples
#![feature(array_chunks)]
let slice = ['l', 'o', 'r', 'e', 'm'];
let mut iter = slice.array_chunks();
assert_eq!(iter.next().unwrap(), &['l', 'o']);
assert_eq!(iter.next().unwrap(), &['r', 'e']);
assert!(iter.next().is_none());
assert_eq!(iter.remainder(), &['m']);
Run
source
pub unsafe fn
as_chunks_unchecked_mut
<const N:
usize
>(
&mut self
) -> &mut [
[T; N]
]
🔬
This is a nightly-only experimental API. (
slice_as_chunks
#74985
)
source
pub unsafe fn
as_chunks_unchecked_mut
<const N:
usize
>(
&mut self
) -> &mut [
[T; N]
]
slice_as_chunks
#74985
)
Splits the slice into a slice of
N
-element arrays,
assuming that there’s no remainder.
Safety
This may only be called when
The slice splits exactly into
N
-element chunks (aka
self.len() % N == 0
).
N != 0
.
Examples
#![feature(slice_as_chunks)]
let slice: &mut [char] = &mut ['l', 'o', 'r', 'e', 'm', '!'];
let chunks: &mut [[char; 1]] =
// SAFETY: 1-element chunks never have remainder
unsafe { slice.as_chunks_unchecked_mut() };
chunks[0] = ['L'];
assert_eq!(chunks, &[['L'], ['o'], ['r'], ['e'], ['m'], ['!']]);
let chunks: &mut [[char; 3]] =
// SAFETY: The slice length (6) is a multiple of 3
unsafe { slice.as_chunks_unchecked_mut() };
chunks[1] = ['a', 'x', '?'];
assert_eq!(slice, &['L', 'o', 'r', 'a', 'x', '?']);
// These would be unsound:
// let chunks: &[[_; 5]] = slice.as_chunks_unchecked_mut() // The slice length is not a multiple of 5
// let chunks: &[[_; 0]] = slice.as_chunks_unchecked_mut() // Zero-length chunks are never allowed
Run
source
pub fn
as_chunks_mut
<const N:
usize
>(&mut self) -> (&mut [
[T; N]
], &mut
[T]
)
🔬
This is a nightly-only experimental API. (
slice_as_chunks
#74985
)
source
pub fn
as_chunks_mut
<const N:
usize
>(&mut self) -> (&mut [
[T; N]
], &mut
[T]
)
slice_as_chunks
#74985
)
Splits the slice into a slice of
N
-element arrays,
starting at the beginning of the slice,
and a remainder slice with length strictly less than
N
.
Panics
Panics if
N
is 0. This check will most probably get changed to a compile time
error before this method gets stabilized.
Examples
#![feature(slice_as_chunks)]
let v = &mut [0, 0, 0, 0, 0];
let mut count = 1;
let (chunks, remainder) = v.as_chunks_mut();
remainder[0] = 9;
for chunk in chunks {
*chunk = [count; 2];
count += 1;
assert_eq!(v, &[1, 1, 2, 2, 9]);
Run
source
pub fn
as_rchunks_mut
<const N:
usize
>(&mut self) -> (&mut
[T]
, &mut [
[T; N]
])
🔬
This is a nightly-only experimental API. (
slice_as_chunks
#74985
)
source
pub fn
as_rchunks_mut
<const N:
usize
>(&mut self) -> (&mut
[T]
, &mut [
[T; N]
])
slice_as_chunks
#74985
)
Splits the slice into a slice of
N
-element arrays,
starting at the end of the slice,
and a remainder slice with length strictly less than
N
.
Panics
Panics if
N
is 0. This check will most probably get changed to a compile time
error before this method gets stabilized.
Examples
#![feature(slice_as_chunks)]
let v = &mut [0, 0, 0, 0, 0];
let mut count = 1;
let (remainder, chunks) = v.as_rchunks_mut();
remainder[0] = 9;
for chunk in chunks {
*chunk = [count; 2];
count += 1;
assert_eq!(v, &[9, 1, 1, 2, 2]);
Run
source
pub fn
array_chunks_mut
<const N:
usize
>(&mut self) ->
ArrayChunksMut
<'_, T, N>
ⓘ
🔬
This is a nightly-only experimental API. (
array_chunks
#74985
)
source
pub fn
array_chunks_mut
<const N:
usize
>(&mut self) ->
ArrayChunksMut
<'_, T, N>
ⓘ
array_chunks
#74985
)
Returns an iterator over
N
elements of the slice at a time, starting at the
beginning of the slice.
The chunks are mutable array references and do not overlap. If
N
does not divide
the length of the slice, then the last up to
N-1
elements will be omitted and
can be retrieved from the
into_remainder
function of the iterator.
This method is the const generic equivalent of
chunks_exact_mut
.
Panics
Panics if
N
is 0. This check will most probably get changed to a compile time
error before this method gets stabilized.
Examples
#![feature(array_chunks)]
let v = &mut [0, 0, 0, 0, 0];
let mut count = 1;
for chunk in v.array_chunks_mut() {
*chunk = [count; 2];
count += 1;
assert_eq!(v, &[1, 1, 2, 2, 0]);
Run
source
pub fn
array_windows
<const N:
usize
>(&self) ->
ArrayWindows
<'_, T, N>
ⓘ
🔬
This is a nightly-only experimental API. (
array_windows
#75027
)
source
pub fn
array_windows
<const N:
usize
>(&self) ->
ArrayWindows
<'_, T, N>
ⓘ
array_windows
#75027
)
Returns an iterator over overlapping windows of
N
elements of a slice,
starting at the beginning of the slice.
This is the const generic equivalent of
windows
.
If
N
is greater than the size of the slice, it will return no windows.
Panics
Panics if
N
is 0. This check will most probably get changed to a compile time
error before this method gets stabilized.
Examples
#![feature(array_windows)]
let slice = [0, 1, 2, 3];
let mut iter = slice.array_windows();
assert_eq!(iter.next().unwrap(), &[0, 1]);
assert_eq!(iter.next().unwrap(), &[1, 2]);
assert_eq!(iter.next().unwrap(), &[2, 3]);
assert!(iter.next().is_none());
Run
1.31.0
·
source
pub fn
rchunks
(&self, chunk_size:
usize
) ->
RChunks
<'_, T>
ⓘ
1.31.0
·
source
pub fn
rchunks
(&self, chunk_size:
usize
) ->
RChunks
<'_, T>
ⓘ
Returns an iterator over
chunk_size
elements of the slice at a time, starting at the end
of the slice.
The chunks are slices and do not overlap. If
chunk_size
does not divide the length of the
slice, then the last chunk will not have length
chunk_size
.
See
rchunks_exact
for a variant of this iterator that returns chunks of always exactly
chunk_size
elements, and
chunks
for the same iterator but starting at the beginning
of the slice.
Panics
Panics if
chunk_size
is 0.
Examples
let slice = ['l', 'o', 'r', 'e', 'm'];
let mut iter = slice.rchunks(2);
assert_eq!(iter.next().unwrap(), &['e', 'm']);
assert_eq!(iter.next().unwrap(), &['o', 'r']);
assert_eq!(iter.next().unwrap(), &['l']);
assert!(iter.next().is_none());
Run
1.31.0
·
source
pub fn
rchunks_mut
(&mut self, chunk_size:
usize
) ->
RChunksMut
<'_, T>
ⓘ
1.31.0
·
source
pub fn
rchunks_mut
(&mut self, chunk_size:
usize
) ->
RChunksMut
<'_, T>
ⓘ
Returns an iterator over
chunk_size
elements of the slice at a time, starting at the end
of the slice.
The chunks are mutable slices, and do not overlap. If
chunk_size
does not divide the
length of the slice, then the last chunk will not have length
chunk_size
.
See
rchunks_exact_mut
for a variant of this iterator that returns chunks of always
exactly
chunk_size
elements, and
chunks_mut
for the same iterator but starting at the
beginning of the slice.
Panics
Panics if
chunk_size
is 0.
Examples
let v = &mut [0, 0, 0, 0, 0];
let mut count = 1;
for chunk in v.rchunks_mut(2) {
for elem in chunk.iter_mut() {
*elem += count;
count += 1;
assert_eq!(v, &[3, 2, 2, 1, 1]);
Run
1.31.0
·
source
pub fn
rchunks_exact
(&self, chunk_size:
usize
) ->
RChunksExact
<'_, T>
ⓘ
1.31.0
·
source
pub fn
rchunks_exact
(&self, chunk_size:
usize
) ->
RChunksExact
<'_, T>
ⓘ
Returns an iterator over
chunk_size
elements of the slice at a time, starting at the
end of the slice.
The chunks are slices and do not overlap. If
chunk_size
does not divide the length of the
slice, then the last up to
chunk_size-1
elements will be omitted and can be retrieved
from the
remainder
function of the iterator.
Due to each chunk having exactly
chunk_size
elements, the compiler can often optimize the
resulting code better than in the case of
rchunks
.
See
rchunks
for a variant of this iterator that also returns the remainder as a smaller
chunk, and
chunks_exact
for the same iterator but starting at the beginning of the
slice.
Panics
Panics if
chunk_size
is 0.
Examples
let slice = ['l', 'o', 'r', 'e', 'm'];
let mut iter = slice.rchunks_exact(2);
assert_eq!(iter.next().unwrap(), &['e', 'm']);
assert_eq!(iter.next().unwrap(), &['o', 'r']);
assert!(iter.next().is_none());
assert_eq!(iter.remainder(), &['l']);
Run
1.31.0
·
source
pub fn
rchunks_exact_mut
(&mut self, chunk_size:
usize
) ->
RChunksExactMut
<'_, T>
ⓘ
1.31.0
·
source
pub fn
rchunks_exact_mut
(&mut self, chunk_size:
usize
) ->
RChunksExactMut
<'_, T>
ⓘ
Returns an iterator over
chunk_size
elements of the slice at a time, starting at the end
of the slice.
The chunks are mutable slices, and do not overlap. If
chunk_size
does not divide the
length of the slice, then the last up to
chunk_size-1
elements will be omitted and can be
retrieved from the
into_remainder
function of the iterator.
Due to each chunk having exactly
chunk_size
elements, the compiler can often optimize the
resulting code better than in the case of
chunks_mut
.
See
rchunks_mut
for a variant of this iterator that also returns the remainder as a
smaller chunk, and
chunks_exact_mut
for the same iterator but starting at the beginning
of the slice.
Panics
Panics if
chunk_size
is 0.
Examples
let v = &mut [0, 0, 0, 0, 0];
let mut count = 1;
for chunk in v.rchunks_exact_mut(2) {
for elem in chunk.iter_mut() {
*elem += count;
count += 1;
assert_eq!(v, &[0, 2, 2, 1, 1]);
Run
source
pub fn
group_by
<F>(&self, pred: F) ->
GroupBy
<'_, T, F>
ⓘ
where
F:
FnMut
(
&T
,
&T
) ->
bool
,
🔬
This is a nightly-only experimental API. (
slice_group_by
#80552
)
source
pub fn
group_by
<F>(&self, pred: F) ->
GroupBy
<'_, T, F>
ⓘ
where
F:
FnMut
(
&T
,
&T
) ->
bool
,
slice_group_by
#80552
)
Returns an iterator over the slice producing non-overlapping runs
of elements using the predicate to separate them.
The predicate is called on two elements following themselves,
it means the predicate is called on
slice[0]
and
slice[1]
then on
slice[1]
and
slice[2]
and so on.
Examples
#![feature(slice_group_by)]
let slice = &[1, 1, 1, 3, 3, 2, 2, 2];
let mut iter = slice.group_by(|a, b| a == b);
assert_eq!(iter.next(), Some(&[1, 1, 1][..]));
assert_eq!(iter.next(), Some(&[3, 3][..]));
assert_eq!(iter.next(), Some(&[2, 2, 2][..]));
assert_eq!(iter.next(), None);
Run
This method can be used to extract the sorted subslices:
#![feature(slice_group_by)]
let slice = &[1, 1, 2, 3, 2, 3, 2, 3, 4];
let mut iter = slice.group_by(|a, b| a <= b);
assert_eq!(iter.next(), Some(&[1, 1, 2, 3][..]));
assert_eq!(iter.next(), Some(&[2, 3][..]));
assert_eq!(iter.next(), Some(&[2, 3, 4][..]));
assert_eq!(iter.next(), None);
Run
source
pub fn
group_by_mut
<F>(&mut self, pred: F) ->
GroupByMut
<'_, T, F>
ⓘ
where
F:
FnMut
(
&T
,
&T
) ->
bool
,
🔬
This is a nightly-only experimental API. (
slice_group_by
#80552
)
source
pub fn
group_by_mut
<F>(&mut self, pred: F) ->
GroupByMut
<'_, T, F>
ⓘ
where
F:
FnMut
(
&T
,
&T
) ->
bool
,
slice_group_by
#80552
)
Returns an iterator over the slice producing non-overlapping mutable
runs of elements using the predicate to separate them.
The predicate is called on two elements following themselves,
it means the predicate is called on
slice[0]
and
slice[1]
then on
slice[1]
and
slice[2]
and so on.
Examples
#![feature(slice_group_by)]
let slice = &mut [1, 1, 1, 3, 3, 2, 2, 2];
let mut iter = slice.group_by_mut(|a, b| a == b);
assert_eq!(iter.next(), Some(&mut [1, 1, 1][..]));
assert_eq!(iter.next(), Some(&mut [3, 3][..]));
assert_eq!(iter.next(), Some(&mut [2, 2, 2][..]));
assert_eq!(iter.next(), None);
Run
This method can be used to extract the sorted subslices:
#![feature(slice_group_by)]
let slice = &mut [1, 1, 2, 3, 2, 3, 2, 3, 4];
let mut iter = slice.group_by_mut(|a, b| a <= b);
assert_eq!(iter.next(), Some(&mut [1, 1, 2, 3][..]));
assert_eq!(iter.next(), Some(&mut [2, 3][..]));
assert_eq!(iter.next(), Some(&mut [2, 3, 4][..]));
assert_eq!(iter.next(), None);
Run
source
pub fn
split_at
(&self, mid:
usize
) -> (&
[T]
, &
[T]
)
source
pub fn
split_at
(&self, mid:
usize
) -> (&
[T]
, &
[T]
)
Divides one slice into two at an index.
The first will contain all indices from
[0, mid)
(excluding
the index
mid
itself) and the second will contain all
indices from
[mid, len)
(excluding the index
len
itself).
Panics
Panics if
mid > len
.
Examples
let v = [1, 2, 3, 4, 5, 6];
let (left, right) = v.split_at(0);
assert_eq!(left, []);
assert_eq!(right, [1, 2, 3, 4, 5, 6]);
let (left, right) = v.split_at(2);
assert_eq!(left, [1, 2]);
assert_eq!(right, [3, 4, 5, 6]);
let (left, right) = v.split_at(6);
assert_eq!(left, [1, 2, 3, 4, 5, 6]);
assert_eq!(right, []);
}
Run
source
pub fn
split_at_mut
(&mut self, mid:
usize
) -> (&mut
[T]
, &mut
[T]
)
source
pub fn
split_at_mut
(&mut self, mid:
usize
) -> (&mut
[T]
, &mut
[T]
)
Divides one mutable slice into two at an index.
The first will contain all indices from
[0, mid)
(excluding
the index
mid
itself) and the second will contain all
indices from
[mid, len)
(excluding the index
len
itself).
Panics
Panics if
mid > len
.
Examples
let mut v = [1, 0, 3, 0, 5, 6];
let (left, right) = v.split_at_mut(2);
assert_eq!(left, [1, 0]);
assert_eq!(right, [3, 0, 5, 6]);
left[1] = 2;
right[1] = 4;
assert_eq!(v, [1, 2, 3, 4, 5, 6]);
Run
source
pub unsafe fn
split_at_unchecked
(&self, mid:
usize
) -> (&
[T]
, &
[T]
)
🔬
This is a nightly-only experimental API. (
slice_split_at_unchecked
#76014
)
source
pub unsafe fn
split_at_unchecked
(&self, mid:
usize
) -> (&
[T]
, &
[T]
)
slice_split_at_unchecked
#76014
)
Divides one slice into two at an index, without doing bounds checking.
The first will contain all indices from
[0, mid)
(excluding
the index
mid
itself) and the second will contain all
indices from
[mid, len)
(excluding the index
len
itself).
For a safe alternative see
split_at
.
Safety
Calling this method with an out-of-bounds index is
undefined behavior
even if the resulting reference is not used. The caller has to ensure that
0 <= mid <= self.len()
.
Examples
#![feature(slice_split_at_unchecked)]
let v = [1, 2, 3, 4, 5, 6];
unsafe {
let (left, right) = v.split_at_unchecked(0);
assert_eq!(left, []);
assert_eq!(right, [1, 2, 3, 4, 5, 6]);
unsafe {
let (left, right) = v.split_at_unchecked(2);
assert_eq!(left, [1, 2]);
assert_eq!(right, [3, 4, 5, 6]);
unsafe {
let (left, right) = v.split_at_unchecked(6);
assert_eq!(left, [1, 2, 3, 4, 5, 6]);
assert_eq!(right, []);
}
Run
source
pub unsafe fn
split_at_mut_unchecked
(
&mut self,
mid:
usize
) -> (&mut
[T]
, &mut
[T]
)
🔬
This is a nightly-only experimental API. (
slice_split_at_unchecked
#76014
)
source
pub unsafe fn
split_at_mut_unchecked
(
&mut self,
mid:
usize
) -> (&mut
[T]
, &mut
[T]
)
slice_split_at_unchecked
#76014
)
Divides one mutable slice into two at an index, without doing bounds checking.
The first will contain all indices from
[0, mid)
(excluding
the index
mid
itself) and the second will contain all
indices from
[mid, len)
(excluding the index
len
itself).
For a safe alternative see
split_at_mut
.
Safety
Calling this method with an out-of-bounds index is
undefined behavior
even if the resulting reference is not used. The caller has to ensure that
0 <= mid <= self.len()
.
Examples
#![feature(slice_split_at_unchecked)]
let mut v = [1, 0, 3, 0, 5, 6];
// scoped to restrict the lifetime of the borrows
unsafe {
let (left, right) = v.split_at_mut_unchecked(2);
assert_eq!(left, [1, 0]);
assert_eq!(right, [3, 0, 5, 6]);
left[1] = 2;
right[1] = 4;
assert_eq!(v, [1, 2, 3, 4, 5, 6]);
Run
source
pub fn
split_array_ref
<const N:
usize
>(&self) -> (&
[T; N]
, &
[T]
)
🔬
This is a nightly-only experimental API. (
split_array
#90091
)
source
pub fn
split_array_ref
<const N:
usize
>(&self) -> (&
[T; N]
, &
[T]
)
split_array
#90091
)
Divides one slice into an array and a remainder slice at an index.
The array will contain all indices from
[0, N)
(excluding
the index
N
itself) and the slice will contain all
indices from
[N, len)
(excluding the index
len
itself).
Panics
Panics if
N > len
.
Examples
#![feature(split_array)]
let v = &[1, 2, 3, 4, 5, 6][..];
let (left, right) = v.split_array_ref::<0>();
assert_eq!(left, &[]);
assert_eq!(right, [1, 2, 3, 4, 5, 6]);
let (left, right) = v.split_array_ref::<2>();
assert_eq!(left, &[1, 2]);
assert_eq!(right, [3, 4, 5, 6]);
let (left, right) = v.split_array_ref::<6>();
assert_eq!(left, &[1, 2, 3, 4, 5, 6]);
assert_eq!(right, []);
}
Run
source
pub fn
split_array_mut
<const N:
usize
>(&mut self) -> (&mut
[T; N]
, &mut
[T]
)
🔬
This is a nightly-only experimental API. (
split_array
#90091
)
source
pub fn
split_array_mut
<const N:
usize
>(&mut self) -> (&mut
[T; N]
, &mut
[T]
)
split_array
#90091
)
Divides one mutable slice into an array and a remainder slice at an index.
The array will contain all indices from
[0, N)
(excluding
the index
N
itself) and the slice will contain all
indices from
[N, len)
(excluding the index
len
itself).
Panics
Panics if
N > len
.
Examples
#![feature(split_array)]
let mut v = &mut [1, 0, 3, 0, 5, 6][..];
let (left, right) = v.split_array_mut::<2>();
assert_eq!(left, &mut [1, 0]);
assert_eq!(right, [3, 0, 5, 6]);
left[1] = 2;
right[1] = 4;
assert_eq!(v, [1, 2, 3, 4, 5, 6]);
Run
source
pub fn
rsplit_array_ref
<const N:
usize
>(&self) -> (&
[T]
, &
[T; N]
)
🔬
This is a nightly-only experimental API. (
split_array
#90091
)
source
pub fn
rsplit_array_ref
<const N:
usize
>(&self) -> (&
[T]
, &
[T; N]
)
split_array
#90091
)
Divides one slice into an array and a remainder slice at an index from
the end.
The slice will contain all indices from
[0, len - N)
(excluding
the index
len - N
itself) and the array will contain all
indices from
[len - N, len)
(excluding the index
len
itself).
Panics
Panics if
N > len
.
Examples
#![feature(split_array)]
let v = &[1, 2, 3, 4, 5, 6][..];
let (left, right) = v.rsplit_array_ref::<0>();
assert_eq!(left, [1, 2, 3, 4, 5, 6]);
assert_eq!(right, &[]);
let (left, right) = v.rsplit_array_ref::<2>();
assert_eq!(left, [1, 2, 3, 4]);
assert_eq!(right, &[5, 6]);
let (left, right) = v.rsplit_array_ref::<6>();
assert_eq!(left, []);
assert_eq!(right, &[1, 2, 3, 4, 5, 6]);
}
Run
source
pub fn
rsplit_array_mut
<const N:
usize
>(&mut self) -> (&mut
[T]
, &mut
[T; N]
)
🔬
This is a nightly-only experimental API. (
split_array
#90091
)
source
pub fn
rsplit_array_mut
<const N:
usize
>(&mut self) -> (&mut
[T]
, &mut
[T; N]
)
split_array
#90091
)
Divides one mutable slice into an array and a remainder slice at an
index from the end.
The slice will contain all indices from
[0, len - N)
(excluding
the index
N
itself) and the array will contain all
indices from
[len - N, len)
(excluding the index
len
itself).
Panics
Panics if
N > len
.
Examples
#![feature(split_array)]
let mut v = &mut [1, 0, 3, 0, 5, 6][..];
let (left, right) = v.rsplit_array_mut::<4>();
assert_eq!(left, [1, 0]);
assert_eq!(right, &mut [3, 0, 5, 6]);
left[1] = 2;
right[1] = 4;
assert_eq!(v, [1, 2, 3, 4, 5, 6]);
Run
source
pub fn
split
<F>(&self, pred: F) ->
Split
<'_, T, F>
ⓘ
where
F:
FnMut
(
&T
) ->
bool
,
source
pub fn
split
<F>(&self, pred: F) ->
Split
<'_, T, F>
ⓘ
where
F:
FnMut
(
&T
) ->
bool
,
Returns an iterator over subslices separated by elements that match
pred
. The matched element is not contained in the subslices.
Examples
let slice = [10, 40, 33, 20];
let mut iter = slice.split(|num| num % 3 == 0);
assert_eq!(iter.next().unwrap(), &[10, 40]);
assert_eq!(iter.next().unwrap(), &[20]);
assert!(iter.next().is_none());
Run
If the first element is matched, an empty slice will be the first item
returned by the iterator. Similarly, if the last element in the slice
is matched, an empty slice will be the last item returned by the
iterator:
let slice = [10, 40, 33];
let mut iter = slice.split(|num| num % 3 == 0);
assert_eq!(iter.next().unwrap(), &[10, 40]);
assert_eq!(iter.next().unwrap(), &[]);
assert!(iter.next().is_none());
Run
If two matched elements are directly adjacent, an empty slice will be
present between them:
let slice = [10, 6, 33, 20];
let mut iter = slice.split(|num| num % 3 == 0);
assert_eq!(iter.next().unwrap(), &[10]);
assert_eq!(iter.next().unwrap(), &[]);
assert_eq!(iter.next().unwrap(), &[20]);
assert!(iter.next().is_none());
Run
source
pub fn
split_mut
<F>(&mut self, pred: F) ->
SplitMut
<'_, T, F>
ⓘ
where
F:
FnMut
(
&T
) ->
bool
,
source
pub fn
split_mut
<F>(&mut self, pred: F) ->
SplitMut
<'_, T, F>
ⓘ
where
F:
FnMut
(
&T
) ->
bool
,
1.51.0
·
source
pub fn
split_inclusive
<F>(&self, pred: F) ->
SplitInclusive
<'_, T, F>
ⓘ
where
F:
FnMut
(
&T
) ->
bool
,
1.51.0
·
source
pub fn
split_inclusive
<F>(&self, pred: F) ->
SplitInclusive
<'_, T, F>
ⓘ
where
F:
FnMut
(
&T
) ->
bool
,
Returns an iterator over subslices separated by elements that match
pred
. The matched element is contained in the end of the previous
subslice as a terminator.
Examples
let slice = [10, 40, 33, 20];
let mut iter = slice.split_inclusive(|num| num % 3 == 0);
assert_eq!(iter.next().unwrap(), &[10, 40, 33]);
assert_eq!(iter.next().unwrap(), &[20]);
assert!(iter.next().is_none());
Run
If the last element of the slice is matched,
that element will be considered the terminator of the preceding slice.
That slice will be the last item returned by the iterator.
let slice = [3, 10, 40, 33];
let mut iter = slice.split_inclusive(|num| num % 3 == 0);
assert_eq!(iter.next().unwrap(), &[3]);
assert_eq!(iter.next().unwrap(), &[10, 40, 33]);
assert!(iter.next().is_none());
Run
1.51.0
·
source
pub fn
split_inclusive_mut
<F>(&mut self, pred: F) ->
SplitInclusiveMut
<'_, T, F>
ⓘ
where
F:
FnMut
(
&T
) ->
bool
,
1.51.0
·
source
pub fn
split_inclusive_mut
<F>(&mut self, pred: F) ->
SplitInclusiveMut
<'_, T, F>
ⓘ
where
F:
FnMut
(
&T
) ->
bool
,
Returns an iterator over mutable subslices separated by elements that
match
pred
. The matched element is contained in the previous
subslice as a terminator.
Examples
let mut v = [10, 40, 30, 20, 60, 50];
for group in v.split_inclusive_mut(|num| *num % 3 == 0) {
let terminator_idx = group.len()-1;
group[terminator_idx] = 1;
assert_eq!(v, [10, 40, 1, 20, 1, 1]);
Run
1.27.0
·
source
pub fn
rsplit
<F>(&self, pred: F) ->
RSplit
<'_, T, F>
ⓘ
where
F:
FnMut
(
&T
) ->
bool
,
1.27.0
·
source
pub fn
rsplit
<F>(&self, pred: F) ->
RSplit
<'_, T, F>
ⓘ
where
F:
FnMut
(
&T
) ->
bool
,
Returns an iterator over subslices separated by elements that match
pred
, starting at the end of the slice and working backwards.
The matched element is not contained in the subslices.
Examples
let slice = [11, 22, 33, 0, 44, 55];
let mut iter = slice.rsplit(|num| *num == 0);
assert_eq!(iter.next().unwrap(), &[44, 55]);
assert_eq!(iter.next().unwrap(), &[11, 22, 33]);
assert_eq!(iter.next(), None);
Run
As with
split()
, if the first or last element is matched, an empty
slice will be the first (or last) item returned by the iterator.
let v = &[0, 1, 1, 2, 3, 5, 8];
let mut it = v.rsplit(|n| *n % 2 == 0);
assert_eq!(it.next().unwrap(), &[]);
assert_eq!(it.next().unwrap(), &[3, 5]);
assert_eq!(it.next().unwrap(), &[1, 1]);
assert_eq!(it.next().unwrap(), &[]);
assert_eq!(it.next(), None);
Run
1.27.0
·
source
pub fn
rsplit_mut
<F>(&mut self, pred: F) ->
RSplitMut
<'_, T, F>
ⓘ
where
F:
FnMut
(
&T
) ->
bool
,
1.27.0
·
source
pub fn
rsplit_mut
<F>(&mut self, pred: F) ->
RSplitMut
<'_, T, F>
ⓘ
where
F:
FnMut
(
&T
) ->
bool
,
Returns an iterator over mutable subslices separated by elements that
match
pred
, starting at the end of the slice and working
backwards. The matched element is not contained in the subslices.
Examples
let mut v = [100, 400, 300, 200, 600, 500];
let mut count = 0;
for group in v.rsplit_mut(|num| *num % 3 == 0) {
count += 1;
group[0] = count;
assert_eq!(v, [3, 400, 300, 2, 600, 1]);
Run
source
pub fn
splitn
<F>(&self, n:
usize
, pred: F) ->
SplitN
<'_, T, F>
ⓘ
where
F:
FnMut
(
&T
) ->
bool
,
source
pub fn
splitn
<F>(&self, n:
usize
, pred: F) ->
SplitN
<'_, T, F>
ⓘ
where
F:
FnMut
(
&T
) ->
bool
,
Returns an iterator over subslices separated by elements that match
pred
, limited to returning at most
n
items. The matched element is
not contained in the subslices.
The last element returned, if any, will contain the remainder of the
slice.
Examples
Print the slice split once by numbers divisible by 3 (i.e.,
[10, 40]
,
[20, 60, 50]
):
let v = [10, 40, 30, 20, 60, 50];
for group in v.splitn(2, |num| *num % 3 == 0) {
println!("{group:?}");
}
Run
source
pub fn
splitn_mut
<F>(&mut self, n:
usize
, pred: F) ->
SplitNMut
<'_, T, F>
ⓘ
where
F:
FnMut
(
&T
) ->
bool
,
source
pub fn
splitn_mut
<F>(&mut self, n:
usize
, pred: F) ->
SplitNMut
<'_, T, F>
ⓘ
where
F:
FnMut
(
&T
) ->
bool
,
Returns an iterator over mutable subslices separated by elements that match
pred
, limited to returning at most
n
items. The matched element is
not contained in the subslices.
The last element returned, if any, will contain the remainder of the
slice.
Examples
let mut v = [10, 40, 30, 20, 60, 50];
for group in v.splitn_mut(2, |num| *num % 3 == 0) {
group[0] = 1;
assert_eq!(v, [1, 40, 30, 1, 60, 50]);
Run
source
pub fn
rsplitn
<F>(&self, n:
usize
, pred: F) ->
RSplitN
<'_, T, F>
ⓘ
where
F:
FnMut
(
&T
) ->
bool
,
source
pub fn
rsplitn
<F>(&self, n:
usize
, pred: F) ->
RSplitN
<'_, T, F>
ⓘ
where
F:
FnMut
(
&T
) ->
bool
,
Returns an iterator over subslices separated by elements that match
pred
limited to returning at most
n
items. This starts at the end of
the slice and works backwards. The matched element is not contained in
the subslices.
The last element returned, if any, will contain the remainder of the
slice.
Examples
Print the slice split once, starting from the end, by numbers divisible
by 3 (i.e.,
[50]
,
[10, 40, 30, 20]
):
let v = [10, 40, 30, 20, 60, 50];
for group in v.rsplitn(2, |num| *num % 3 == 0) {
println!("{group:?}");
}
Run
source
pub fn
rsplitn_mut
<F>(&mut self, n:
usize
, pred: F) ->
RSplitNMut
<'_, T, F>
ⓘ
where
F:
FnMut
(
&T
) ->
bool
,
source
pub fn
rsplitn_mut
<F>(&mut self, n:
usize
, pred: F) ->
RSplitNMut
<'_, T, F>
ⓘ
where
F:
FnMut
(
&T
) ->
bool
,
Returns an iterator over subslices separated by elements that match
pred
limited to returning at most
n
items. This starts at the end of
the slice and works backwards. The matched element is not contained in
the subslices.
The last element returned, if any, will contain the remainder of the
slice.
Examples
let mut s = [10, 40, 30, 20, 60, 50];
for group in s.rsplitn_mut(2, |num| *num % 3 == 0) {
group[0] = 1;
assert_eq!(s, [1, 40, 30, 20, 60, 1]);
Run
source
pub fn
contains
(&self, x:
&T
) ->
bool
where
T:
PartialEq
<T>,
source
pub fn
contains
(&self, x:
&T
) ->
bool
where
T:
PartialEq
<T>,
Returns
true
if the slice contains an element with the given value.
This operation is
O
(
n
).
Note that if you have a sorted slice,
binary_search
may be faster.
Examples
let v = [10, 40, 30];
assert!(v.contains(&30));
assert!(!v.contains(&50));
Run
If you do not have a
&T
, but some other value that you can compare
with one (for example,
String
implements
PartialEq<str>
), you can
use
iter().any
:
let v = [String::from("hello"), String::from("world")]; // slice of `String`
assert!(v.iter().any(|e| e == "hello")); // search with `&str`
assert!(!v.iter().any(|e| e == "hi"));
Run
source
pub fn
starts_with
(&self, needle: &
[T]
) ->
bool
where
T:
PartialEq
<T>,
source
pub fn
starts_with
(&self, needle: &
[T]
) ->
bool
where
T:
PartialEq
<T>,
Returns
true
if
needle
is a prefix of the slice.
Examples
let v = [10, 40, 30];
assert!(v.starts_with(&[10]));
assert!(v.starts_with(&[10, 40]));
assert!(!v.starts_with(&[50]));
assert!(!v.starts_with(&[10, 50]));
Run
Always returns
true
if
needle
is an empty slice:
let v = &[10, 40, 30];
assert!(v.starts_with(&[]));
let v: &[u8] = &[];
assert!(v.starts_with(&[]));
Run
source
pub fn
ends_with
(&self, needle: &
[T]
) ->
bool
where
T:
PartialEq
<T>,
source
pub fn
ends_with
(&self, needle: &
[T]
) ->
bool
where
T:
PartialEq
<T>,
Returns
true
if
needle
is a suffix of the slice.
Examples
let v = [10, 40, 30];
assert!(v.ends_with(&[30]));
assert!(v.ends_with(&[40, 30]));
assert!(!v.ends_with(&[50]));
assert!(!v.ends_with(&[50, 30]));
Run
Always returns
true
if
needle
is an empty slice:
let v = &[10, 40, 30];
assert!(v.ends_with(&[]));
let v: &[u8] = &[];
assert!(v.ends_with(&[]));
Run
1.51.0
·
source
pub fn
strip_prefix
<P>(&self, prefix:
&P
) ->
Option
<&
[T]
>
where
P:
SlicePattern
<Item = T> + ?
Sized
,
T:
PartialEq
<T>,
1.51.0
·
source
pub fn
strip_prefix
<P>(&self, prefix:
&P
) ->
Option
<&
[T]
>
where
P:
SlicePattern
<Item = T> + ?
Sized
,
T:
PartialEq
<T>,
Returns a subslice with the prefix removed.
If the slice starts with
prefix
, returns the subslice after the prefix, wrapped in
Some
.
If
prefix
is empty, simply returns the original slice.
If the slice does not start with
prefix
, returns
None
.
Examples
let v = &[10, 40, 30];
assert_eq!(v.strip_prefix(&[10]), Some(&[40, 30][..]));
assert_eq!(v.strip_prefix(&[10, 40]), Some(&[30][..]));
assert_eq!(v.strip_prefix(&[50]), None);
assert_eq!(v.strip_prefix(&[10, 50]), None);
let prefix : &str = "he";
assert_eq!(b"hello".strip_prefix(prefix.as_bytes()),
Some(b"llo".as_ref()));
Run
1.51.0
·
source
pub fn
strip_suffix
<P>(&self, suffix:
&P
) ->
Option
<&
[T]
>
where
P:
SlicePattern
<Item = T> + ?
Sized
,
T:
PartialEq
<T>,
1.51.0
·
source
pub fn
strip_suffix
<P>(&self, suffix:
&P
) ->
Option
<&
[T]
>
where
P:
SlicePattern
<Item = T> + ?
Sized
,
T:
PartialEq
<T>,
Returns a subslice with the suffix removed.
If the slice ends with
suffix
, returns the subslice before the suffix, wrapped in
Some
.
If
suffix
is empty, simply returns the original slice.
If the slice does not end with
suffix
, returns
None
.
Examples
let v = &[10, 40, 30];
assert_eq!(v.strip_suffix(&[30]), Some(&[10, 40][..]));
assert_eq!(v.strip_suffix(&[40, 30]), Some(&[10][..]));
assert_eq!(v.strip_suffix(&[50]), None);
assert_eq!(v.strip_suffix(&[50, 30]), None);
Run
source
pub fn
binary_search
(&self, x:
&T
) ->
Result
<
usize
,
usize
>
where
T:
Ord
,
source
pub fn
binary_search
(&self, x:
&T
) ->
Result
<
usize
,
usize
>
where
T:
Ord
,
Binary searches this slice for a given element.
If the slice is not sorted, the returned result is unspecified and
meaningless.
If the value is found then
Result::Ok
is returned, containing the
index of the matching element. If there are multiple matches, then any
one of the matches could be returned. The index is chosen
deterministically, but is subject to change in future versions of Rust.
If the value is not found then
Result::Err
is returned, containing
the index where a matching element could be inserted while maintaining
sorted order.
See also
binary_search_by
,
binary_search_by_key
, and
partition_point
.
Examples
Looks up a series of four elements. The first is found, with a
uniquely determined position; the second and third are not
found; the fourth could match any position in
[1, 4]
.
let s = [0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55];
assert_eq!(s.binary_search(&13), Ok(9));
assert_eq!(s.binary_search(&4), Err(7));
assert_eq!(s.binary_search(&100), Err(13));
let r = s.binary_search(&1);
assert!(match r { Ok(1..=4) => true, _ => false, });
Run
If you want to find that whole
range
of matching items, rather than
an arbitrary matching one, that can be done using
partition_point
:
let s = [0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55];
let low = s.partition_point(|x| x < &1);
assert_eq!(low, 1);
let high = s.partition_point(|x| x <= &1);
assert_eq!(high, 5);
let r = s.binary_search(&1);
assert!((low..high).contains(&r.unwrap()));
assert!(s[..low].iter().all(|&x| x < 1));
assert!(s[low..high].iter().all(|&x| x == 1));
assert!(s[high..].iter().all(|&x| x > 1));
// For something not found, the "range" of equal items is empty
assert_eq!(s.partition_point(|x| x < &11), 9);
assert_eq!(s.partition_point(|x| x <= &11), 9);
assert_eq!(s.binary_search(&11), Err(9));
Run
If you want to insert an item to a sorted vector, while maintaining
sort order, consider using
partition_point
:
let mut s = vec![0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55];
let num = 42;
let idx = s.partition_point(|&x| x < num);
// The above is equivalent to `let idx = s.binary_search(&num).unwrap_or_else(|x| x);`
s.insert(idx, num);
assert_eq!(s, [0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 42, 55]);
Run
source
pub fn
binary_search_by
<'a, F>(&'a self, f: F) ->
Result
<
usize
,
usize
>
where
F:
FnMut
(
&'a T
) ->
Ordering
,
source
pub fn
binary_search_by
<'a, F>(&'a self, f: F) ->
Result
<
usize
,
usize
>
where
F:
FnMut
(
&'a T
) ->
Ordering
,
Binary searches this slice with a comparator function.
The comparator function should return an order code that indicates
whether its argument is
Less
,
Equal
or
Greater
the desired
target.
If the slice is not sorted or if the comparator function does not
implement an order consistent with the sort order of the underlying
slice, the returned result is unspecified and meaningless.
If the value is found then
Result::Ok
is returned, containing the
index of the matching element. If there are multiple matches, then any
one of the matches could be returned. The index is chosen
deterministically, but is subject to change in future versions of Rust.
If the value is not found then
Result::Err
is returned, containing
the index where a matching element could be inserted while maintaining
sorted order.
See also
binary_search
,
binary_search_by_key
, and
partition_point
.
Examples
Looks up a series of four elements. The first is found, with a
uniquely determined position; the second and third are not
found; the fourth could match any position in
[1, 4]
.
let s = [0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55];
let seek = 13;
assert_eq!(s.binary_search_by(|probe| probe.cmp(&seek)), Ok(9));
let seek = 4;
assert_eq!(s.binary_search_by(|probe| probe.cmp(&seek)), Err(7));
let seek = 100;
assert_eq!(s.binary_search_by(|probe| probe.cmp(&seek)), Err(13));
let seek = 1;
let r = s.binary_search_by(|probe| probe.cmp(&seek));
assert!(match r { Ok(1..=4) => true, _ => false, });
Run
1.10.0
·
source
pub fn
binary_search_by_key
<'a, B, F>(
&'a self,
b:
&B
,
) ->
Result
<
usize
,
usize
>
where
F:
FnMut
(
&'a T
) -> B,
B:
Ord
,
1.10.0
·
source
pub fn
binary_search_by_key
<'a, B, F>(
&'a self,
b:
&B
,
) ->
Result
<
usize
,
usize
>
where
F:
FnMut
(
&'a T
) -> B,
B:
Ord
,
Binary searches this slice with a key extraction function.
Assumes that the slice is sorted by the key, for instance with
sort_by_key
using the same key extraction function.
If the slice is not sorted by the key, the returned result is
unspecified and meaningless.
If the value is found then
Result::Ok
is returned, containing the
index of the matching element. If there are multiple matches, then any
one of the matches could be returned. The index is chosen
deterministically, but is subject to change in future versions of Rust.
If the value is not found then
Result::Err
is returned, containing
the index where a matching element could be inserted while maintaining
sorted order.
See also
binary_search
,
binary_search_by
, and
partition_point
.
Examples
Looks up a series of four elements in a slice of pairs sorted by
their second elements. The first is found, with a uniquely
determined position; the second and third are not found; the
fourth could match any position in
[1, 4]
.
let s = [(0, 0), (2, 1), (4, 1), (5, 1), (3, 1),
(1, 2), (2, 3), (4, 5), (5, 8), (3, 13),
(1, 21), (2, 34), (4, 55)];
assert_eq!(s.binary_search_by_key(&13, |&(a, b)| b), Ok(9));
assert_eq!(s.binary_search_by_key(&4, |&(a, b)| b), Err(7));
assert_eq!(s.binary_search_by_key(&100, |&(a, b)| b), Err(13));
let r = s.binary_search_by_key(&1, |&(a, b)| b);
assert!(match r { Ok(1..=4) => true, _ => false, });
Run
1.20.0
·
source
pub fn
sort_unstable
(&mut self)
where
T:
Ord
,
1.20.0
·
source
pub fn
sort_unstable
(&mut self)
where
T:
Ord
,
Sorts the slice, but might not preserve the order of equal elements.
This sort is unstable (i.e., may reorder equal elements), in-place
(i.e., does not allocate), and
O
(
n
* log(
n
)) worst-case.
Current implementation
The current algorithm is based on
pattern-defeating quicksort
by Orson Peters,
which combines the fast average case of randomized quicksort with the fast worst case of
heapsort, while achieving linear time on slices with certain patterns. It uses some
randomization to avoid degenerate cases, but with a fixed seed to always provide
deterministic behavior.
It is typically faster than stable sorting, except in a few special cases, e.g., when the
slice consists of several concatenated sorted sequences.
Examples
let mut v = [-5, 4, 1, -3, 2];
v.sort_unstable();
assert!(v == [-5, -3, 1, 2, 4]);
Run
1.20.0
·
source
pub fn
sort_unstable_by
<F>(&mut self, compare: F)
where
F:
FnMut
(
&T
,
&T
) ->
Ordering
,
1.20.0
·
source
pub fn
sort_unstable_by
<F>(&mut self, compare: F)
where
F:
FnMut
(
&T
,
&T
) ->
Ordering
,
Sorts the slice with a comparator function, but might not preserve the order of equal
elements.
This sort is unstable (i.e., may reorder equal elements), in-place
(i.e., does not allocate), and
O
(
n
* log(
n
)) worst-case.
The comparator function must define a total ordering for the elements in the slice. If
the ordering is not total, the order of the elements is unspecified. An order is a
total order if it is (for all
a
,
b
and
c
):
total and antisymmetric: exactly one of
a < b
,
a == b
or
a > b
is true, and
transitive,
a < b
and
b < c
implies
a < c
. The same must hold for both
==
and
>
.
For example, while
f64
doesn’t implement
Ord
because
NaN != NaN
, we can use
partial_cmp
as our sort function when we know the slice doesn’t contain a
NaN
.
let mut floats = [5f64, 4.0, 1.0, 3.0, 2.0];
floats.sort_unstable_by(|a, b| a.partial_cmp(b).unwrap());
assert_eq!(floats, [1.0, 2.0, 3.0, 4.0, 5.0]);
Run
Current implementation
The current algorithm is based on
pattern-defeating quicksort
by Orson Peters,
which combines the fast average case of randomized quicksort with the fast worst case of
heapsort, while achieving linear time on slices with certain patterns. It uses some
randomization to avoid degenerate cases, but with a fixed seed to always provide
deterministic behavior.
It is typically faster than stable sorting, except in a few special cases, e.g., when the
slice consists of several concatenated sorted sequences.
Examples
let mut v = [5, 4, 1, 3, 2];
v.sort_unstable_by(|a, b| a.cmp(b));
assert!(v == [1, 2, 3, 4, 5]);
// reverse sorting
v.sort_unstable_by(|a, b| b.cmp(a));
assert!(v == [5, 4, 3, 2, 1]);
Run
1.20.0
·
source
pub fn
sort_unstable_by_key
<K, F>(&mut self, f: F)
where
F:
FnMut
(
&T
) -> K,
K:
Ord
,
1.20.0
·
source
pub fn
sort_unstable_by_key
<K, F>(&mut self, f: F)
where
F:
FnMut
(
&T
) -> K,
K:
Ord
,
Sorts the slice with a key extraction function, but might not preserve the order of equal
elements.
This sort is unstable (i.e., may reorder equal elements), in-place
(i.e., does not allocate), and
O
(m *
n
* log(
n
)) worst-case, where the key function is
O
(
m
).
Current implementation
The current algorithm is based on
pattern-defeating quicksort
by Orson Peters,
which combines the fast average case of randomized quicksort with the fast worst case of
heapsort, while achieving linear time on slices with certain patterns. It uses some
randomization to avoid degenerate cases, but with a fixed seed to always provide
deterministic behavior.
Due to its key calling strategy,
sort_unstable_by_key
is likely to be slower than
sort_by_cached_key
in
cases where the key function is expensive.
Examples
let mut v = [-5i32, 4, 1, -3, 2];
v.sort_unstable_by_key(|k| k.abs());
assert!(v == [1, 2, -3, 4, -5]);
Run
1.49.0
·
source
pub fn
select_nth_unstable
(
&mut self,
index:
usize
) -> (&mut
[T]
,
&mut T
, &mut
[T]
)
where
T:
Ord
,
1.49.0
·
source
pub fn
select_nth_unstable
(
&mut self,
index:
usize
) -> (&mut
[T]
,
&mut T
, &mut
[T]
)
where
T:
Ord
,
Reorder the slice such that the element at
index
is at its final sorted position.
This reordering has the additional property that any value at position
i < index
will be
less than or equal to any value at a position
j > index
. Additionally, this reordering is
unstable (i.e. any number of equal elements may end up at position
index
), in-place
(i.e. does not allocate), and
O
(
n
) on average. The worst-case performance is
O
(
n
log
n
).
This function is also known as “kth element” in other libraries.
It returns a triplet of the following from the reordered slice:
the subslice prior to
index
, the element at
index
, and the subslice after
index
;
accordingly, the values in those two subslices will respectively all be less-than-or-equal-to
and greater-than-or-equal-to the value of the element at
index
.
Current implementation
The current algorithm is based on the quickselect portion of the same quicksort algorithm
used for
sort_unstable
.
Panics
Panics when
index >= len()
, meaning it always panics on empty slices.
Examples
let mut v = [-5i32, 4, 1, -3, 2];
// Find the median
v.select_nth_unstable(2);
// We are only guaranteed the slice will be one of the following, based on the way we sort
// about the specified index.
assert!(v == [-3, -5, 1, 2, 4] ||
v == [-5, -3, 1, 2, 4] ||
v == [-3, -5, 1, 4, 2] ||
v == [-5, -3, 1, 4, 2]);
Run
1.49.0
·
source
pub fn
select_nth_unstable_by
<F>(
&mut self,
index:
usize
,
compare: F
) -> (&mut
[T]
,
&mut T
, &mut
[T]
)
where
F:
FnMut
(
&T
,
&T
) ->
Ordering
,
1.49.0
·
source
pub fn
select_nth_unstable_by
<F>(
&mut self,
index:
usize
,
compare: F
) -> (&mut
[T]
,
&mut T
, &mut
[T]
)
where
F:
FnMut
(
&T
,
&T
) ->
Ordering
,
Reorder the slice with a comparator function such that the element at
index
is at its
final sorted position.
This reordering has the additional property that any value at position
i < index
will be
less than or equal to any value at a position
j > index
using the comparator function.
Additionally, this reordering is unstable (i.e. any number of equal elements may end up at
position
index
), in-place (i.e. does not allocate), and
O
(
n
) on average.
The worst-case performance is
O
(
n
log
n
). This function is also known as
“kth element” in other libraries.
It returns a triplet of the following from
the slice reordered according to the provided comparator function: the subslice prior to
index
, the element at
index
, and the subslice after
index
; accordingly, the values in
those two subslices will respectively all be less-than-or-equal-to and greater-than-or-equal-to
the value of the element at
index
.
Current implementation
The current algorithm is based on the quickselect portion of the same quicksort algorithm
used for
sort_unstable
.
Panics
Panics when
index >= len()
, meaning it always panics on empty slices.
Examples
let mut v = [-5i32, 4, 1, -3, 2];
// Find the median as if the slice were sorted in descending order.
v.select_nth_unstable_by(2, |a, b| b.cmp(a));
// We are only guaranteed the slice will be one of the following, based on the way we sort
// about the specified index.
assert!(v == [2, 4, 1, -5, -3] ||
v == [2, 4, 1, -3, -5] ||
v == [4, 2, 1, -5, -3] ||
v == [4, 2, 1, -3, -5]);
Run
1.49.0
·
source
pub fn
select_nth_unstable_by_key
<K, F>(
&mut self,
index:
usize
,
) -> (&mut
[T]
,
&mut T
, &mut
[T]
)
where
F:
FnMut
(
&T
) -> K,
K:
Ord
,
1.49.0
·
source
pub fn
select_nth_unstable_by_key
<K, F>(
&mut self,
index:
usize
,
) -> (&mut
[T]
,
&mut T
, &mut
[T]
)
where
F:
FnMut
(
&T
) -> K,
K:
Ord
,
Reorder the slice with a key extraction function such that the element at
index
is at its
final sorted position.
This reordering has the additional property that any value at position
i < index
will be
less than or equal to any value at a position
j > index
using the key extraction function.
Additionally, this reordering is unstable (i.e. any number of equal elements may end up at
position
index
), in-place (i.e. does not allocate), and
O
(
n
) on average.
The worst-case performance is
O
(
n
log
n
).
This function is also known as “kth element” in other libraries.
It returns a triplet of the following from
the slice reordered according to the provided key extraction function: the subslice prior to
index
, the element at
index
, and the subslice after
index
; accordingly, the values in
those two subslices will respectively all be less-than-or-equal-to and greater-than-or-equal-to
the value of the element at
index
.
Current implementation
The current algorithm is based on the quickselect portion of the same quicksort algorithm
used for
sort_unstable
.
Panics
Panics when
index >= len()
, meaning it always panics on empty slices.
Examples
let mut v = [-5i32, 4, 1, -3, 2];
// Return the median as if the array were sorted according to absolute value.
v.select_nth_unstable_by_key(2, |a| a.abs());
// We are only guaranteed the slice will be one of the following, based on the way we sort
// about the specified index.
assert!(v == [1, 2, -3, 4, -5] ||
v == [1, 2, -3, -5, 4] ||
v == [2, 1, -3, 4, -5] ||
v == [2, 1, -3, -5, 4]);
Run
source
pub fn
partition_dedup
(&mut self) -> (&mut
[T]
, &mut
[T]
)
where
T:
PartialEq
<T>,
🔬
This is a nightly-only experimental API. (
slice_partition_dedup
#54279
)
source
pub fn
partition_dedup
(&mut self) -> (&mut
[T]
, &mut
[T]
)
where
T:
PartialEq
<T>,
slice_partition_dedup
#54279
)
Moves all consecutive repeated elements to the end of the slice according to the
PartialEq
trait implementation.
Returns two slices. The first contains no consecutive repeated elements.
The second contains all the duplicates in no specified order.
If the slice is sorted, the first returned slice contains no duplicates.
Examples
#![feature(slice_partition_dedup)]
let mut slice = [1, 2, 2, 3, 3, 2, 1, 1];
let (dedup, duplicates) = slice.partition_dedup();
assert_eq!(dedup, [1, 2, 3, 2, 1]);
assert_eq!(duplicates, [2, 3, 1]);
Run
source
pub fn
partition_dedup_by
<F>(&mut self, same_bucket: F) -> (&mut
[T]
, &mut
[T]
)
where
F:
FnMut
(
&mut T
,
&mut T
) ->
bool
,
🔬
This is a nightly-only experimental API. (
slice_partition_dedup
#54279
)
source
pub fn
partition_dedup_by
<F>(&mut self, same_bucket: F) -> (&mut
[T]
, &mut
[T]
)
where
F:
FnMut
(
&mut T
,
&mut T
) ->
bool
,
slice_partition_dedup
#54279
)
Moves all but the first of consecutive elements to the end of the slice satisfying
a given equality relation.
Returns two slices. The first contains no consecutive repeated elements.
The second contains all the duplicates in no specified order.
The
same_bucket
function is passed references to two elements from the slice and
must determine if the elements compare equal. The elements are passed in opposite order
from their order in the slice, so if
same_bucket(a, b)
returns
true
,
a
is moved
at the end of the slice.
If the slice is sorted, the first returned slice contains no duplicates.
Examples
#![feature(slice_partition_dedup)]
let mut slice = ["foo", "Foo", "BAZ", "Bar", "bar", "baz", "BAZ"];
let (dedup, duplicates) = slice.partition_dedup_by(|a, b| a.eq_ignore_ascii_case(b));
assert_eq!(dedup, ["foo", "BAZ", "Bar", "baz"]);
assert_eq!(duplicates, ["bar", "Foo", "BAZ"]);
Run
source
pub fn
partition_dedup_by_key
<K, F>(&mut self, key: F) -> (&mut
[T]
, &mut
[T]
)
where
F:
FnMut
(
&mut T
) -> K,
K:
PartialEq
<K>,
🔬
This is a nightly-only experimental API. (
slice_partition_dedup
#54279
)
source
pub fn
partition_dedup_by_key
<K, F>(&mut self, key: F) -> (&mut
[T]
, &mut
[T]
)
where
F:
FnMut
(
&mut T
) -> K,
K:
PartialEq
<K>,
slice_partition_dedup
#54279
)
Moves all but the first of consecutive elements to the end of the slice that resolve
to the same key.
Returns two slices. The first contains no consecutive repeated elements.
The second contains all the duplicates in no specified order.
If the slice is sorted, the first returned slice contains no duplicates.
Examples
#![feature(slice_partition_dedup)]
let mut slice = [10, 20, 21, 30, 30, 20, 11, 13];
let (dedup, duplicates) = slice.partition_dedup_by_key(|i| *i / 10);
assert_eq!(dedup, [10, 20, 30, 20, 11]);
assert_eq!(duplicates, [21, 30, 13]);
Run
1.26.0
·
source
pub fn
rotate_left
(&mut self, mid:
usize
)
1.26.0
·
source
pub fn
rotate_left
(&mut self, mid:
usize
)
Rotates the slice in-place such that the first
mid
elements of the
slice move to the end while the last
self.len() - mid
elements move to
the front. After calling
rotate_left
, the element previously at index
mid
will become the first element in the slice.
Panics
This function will panic if
mid
is greater than the length of the
slice. Note that
mid == self.len()
does
not
panic and is a no-op
rotation.
Complexity
Takes linear (in
self.len()
) time.
Examples
let mut a = ['a', 'b', 'c', 'd', 'e', 'f'];
a.rotate_left(2);
assert_eq!(a, ['c', 'd', 'e', 'f', 'a', 'b']);
Run
Rotating a subslice:
let mut a = ['a', 'b', 'c', 'd', 'e', 'f'];
a[1..5].rotate_left(1);
assert_eq!(a, ['a', 'c', 'd', 'e', 'b', 'f']);
Run
1.26.0
·
source
pub fn
rotate_right
(&mut self, k:
usize
)
1.26.0
·
source
pub fn
rotate_right
(&mut self, k:
usize
)
Rotates the slice in-place such that the first
self.len() - k
elements of the slice move to the end while the last
k
elements move
to the front. After calling
rotate_right
, the element previously at
index
self.len() - k
will become the first element in the slice.
Panics
This function will panic if
k
is greater than the length of the
slice. Note that
k == self.len()
does
not
panic and is a no-op
rotation.
Complexity
Takes linear (in
self.len()
) time.
Examples
let mut a = ['a', 'b', 'c', 'd', 'e', 'f'];
a.rotate_right(2);
assert_eq!(a, ['e', 'f', 'a', 'b', 'c', 'd']);
Run
Rotate a subslice:
let mut a = ['a', 'b', 'c', 'd', 'e', 'f'];
a[1..5].rotate_right(1);
assert_eq!(a, ['a', 'e', 'b', 'c', 'd', 'f']);
Run
1.51.0
·
source
pub fn
fill_with
<F>(&mut self, f: F)
where
F:
FnMut
() -> T,
1.51.0
·
source
pub fn
fill_with
<F>(&mut self, f: F)
where
F:
FnMut
() -> T,
Fills
self
with elements returned by calling a closure repeatedly.
This method uses a closure to create new values. If you’d rather
Clone
a given value, use
fill
. If you want to use the
Default
trait to generate values, you can pass
Default::default
as the
argument.
Examples
let mut buf = vec![1; 10];
buf.fill_with(Default::default);
assert_eq!(buf, vec![0; 10]);
Run
1.7.0
·
source
pub fn
clone_from_slice
(&mut self, src: &
[T]
)
where
T:
Clone
,
1.7.0
·
source
pub fn
clone_from_slice
(&mut self, src: &
[T]
)
where
T:
Clone
,
Copies the elements from
src
into
self
.
The length of
src
must be the same as
self
.
Panics
This function will panic if the two slices have different lengths.
Examples
Cloning two elements from a slice into another:
let src = [1, 2, 3, 4];
let mut dst = [0, 0];
// Because the slices have to be the same length,
// we slice the source slice from four elements
// to two. It will panic if we don't do this.
dst.clone_from_slice(&src[2..]);
assert_eq!(src, [1, 2, 3, 4]);
assert_eq!(dst, [3, 4]);
Run
Rust enforces that there can only be one mutable reference with no
immutable references to a particular piece of data in a particular
scope. Because of this, attempting to use
clone_from_slice
on a
single slice will result in a compile failure:
To work around this, we can use
split_at_mut
to create two distinct
sub-slices from a slice:
let mut slice = [1, 2, 3, 4, 5];
let (left, right) = slice.split_at_mut(2);
left.clone_from_slice(&right[1..]);
assert_eq!(slice, [4, 5, 3, 4, 5]);
Run
1.9.0
·
source
pub fn
copy_from_slice
(&mut self, src: &
[T]
)
where
T:
Copy
,
1.9.0
·
source
pub fn
copy_from_slice
(&mut self, src: &
[T]
)
where
T:
Copy
,
Copies all elements from
src
into
self
, using a memcpy.
The length of
src
must be the same as
self
.
If
T
does not implement
Copy
, use
clone_from_slice
.
Panics
This function will panic if the two slices have different lengths.
Examples
Copying two elements from a slice into another:
let src = [1, 2, 3, 4];
let mut dst = [0, 0];
// Because the slices have to be the same length,
// we slice the source slice from four elements
// to two. It will panic if we don't do this.
dst.copy_from_slice(&src[2..]);
assert_eq!(src, [1, 2, 3, 4]);
assert_eq!(dst, [3, 4]);
Run
Rust enforces that there can only be one mutable reference with no
immutable references to a particular piece of data in a particular
scope. Because of this, attempting to use
copy_from_slice
on a
single slice will result in a compile failure:
To work around this, we can use
split_at_mut
to create two distinct
sub-slices from a slice:
let mut slice = [1, 2, 3, 4, 5];
let (left, right) = slice.split_at_mut(2);
left.copy_from_slice(&right[1..]);
assert_eq!(slice, [4, 5, 3, 4, 5]);
Run
1.37.0
·
source
pub fn
copy_within
<R>(&mut self, src: R, dest:
usize
)
where
R:
RangeBounds
<
usize
>,
T:
Copy
,
1.37.0
·
source
pub fn
copy_within
<R>(&mut self, src: R, dest:
usize
)
where
R:
RangeBounds
<
usize
>,
T:
Copy
,
Copies elements from one part of the slice to another part of itself,
using a memmove.
src
is the range within
self
to copy from.
dest
is the starting
index of the range within
self
to copy to, which will have the same
length as
src
. The two ranges may overlap. The ends of the two ranges
must be less than or equal to
self.len()
.
Panics
This function will panic if either range exceeds the end of the slice,
or if the end of
src
is before the start.
Examples
Copying four bytes within a slice:
let mut bytes = *b"Hello, World!";
bytes.copy_within(1..5, 8);
assert_eq!(&bytes, b"Hello, Wello!");
Run
1.27.0
·
source
pub fn
swap_with_slice
(&mut self, other: &mut
[T]
)
1.27.0
·
source
pub fn
swap_with_slice
(&mut self, other: &mut
[T]
)
Swaps all elements in
self
with those in
other
.
The length of
other
must be the same as
self
.
Panics
This function will panic if the two slices have different lengths.
Example
Swapping two elements across slices:
let mut slice1 = [0, 0];
let mut slice2 = [1, 2, 3, 4];
slice1.swap_with_slice(&mut slice2[2..]);
assert_eq!(slice1, [3, 4]);
assert_eq!(slice2, [1, 2, 0, 0]);
Run
Rust enforces that there can only be one mutable reference to a
particular piece of data in a particular scope. Because of this,
attempting to use
swap_with_slice
on a single slice will result in
a compile failure:
ⓘ
let mut slice = [1, 2, 3, 4, 5];
slice[..2].swap_with_slice(&mut slice[3..]); // compile fail!
Run
To work around this, we can use
split_at_mut
to create two distinct
mutable sub-slices from a slice:
let mut slice = [1, 2, 3, 4, 5];
let (left, right) = slice.split_at_mut(2);
left.swap_with_slice(&mut right[1..]);
assert_eq!(slice, [4, 5, 3, 1, 2]);
Run
1.30.0
·
source
pub unsafe fn
align_to
<U>(&self) -> (&
[T]
, &
[U]
, &
[T]
)
1.30.0
·
source
pub unsafe fn
align_to
<U>(&self) -> (&
[T]
, &
[U]
, &
[T]
)
Transmute the slice to a slice of another type, ensuring alignment of the types is
maintained.
This method splits the slice into three distinct slices: prefix, correctly aligned middle
slice of a new type, and the suffix slice. How exactly the slice is split up is not
specified; the middle part may be smaller than necessary. However, if this fails to return a
maximal middle part, that is because code is running in a context where performance does not
matter, such as a sanitizer attempting to find alignment bugs. Regular code running
in a default (debug or release) execution
will
return a maximal middle part.
This method has no purpose when either input element
T
or output element
U
are
zero-sized and will return the original slice without splitting anything.
Safety
This method is essentially a
transmute
with respect to the elements in the returned
middle slice, so all the usual caveats pertaining to
transmute::<T, U>
also apply here.
Examples
Basic usage:
unsafe {
let bytes: [u8; 7] = [1, 2, 3, 4, 5, 6, 7];
let (prefix, shorts, suffix) = bytes.align_to::<u16>();
// less_efficient_algorithm_for_bytes(prefix);
// more_efficient_algorithm_for_aligned_shorts(shorts);
// less_efficient_algorithm_for_bytes(suffix);
}
Run
1.30.0
·
source
pub unsafe fn
align_to_mut
<U>(&mut self) -> (&mut
[T]
, &mut
[U]
, &mut
[T]
)
1.30.0
·
source
pub unsafe fn
align_to_mut
<U>(&mut self) -> (&mut
[T]
, &mut
[U]
, &mut
[T]
)
Transmute the mutable slice to a mutable slice of another type, ensuring alignment of the
types is maintained.
This method splits the slice into three distinct slices: prefix, correctly aligned middle
slice of a new type, and the suffix slice. How exactly the slice is split up is not
specified; the middle part may be smaller than necessary. However, if this fails to return a
maximal middle part, that is because code is running in a context where performance does not
matter, such as a sanitizer attempting to find alignment bugs. Regular code running
in a default (debug or release) execution
will
return a maximal middle part.
This method has no purpose when either input element
T
or output element
U
are
zero-sized and will return the original slice without splitting anything.
Safety
This method is essentially a
transmute
with respect to the elements in the returned
middle slice, so all the usual caveats pertaining to
transmute::<T, U>
also apply here.
Examples
Basic usage:
unsafe {
let mut bytes: [u8; 7] = [1, 2, 3, 4, 5, 6, 7];
let (prefix, shorts, suffix) = bytes.align_to_mut::<u16>();
// less_efficient_algorithm_for_bytes(prefix);
// more_efficient_algorithm_for_aligned_shorts(shorts);
// less_efficient_algorithm_for_bytes(suffix);
}
Run
source
pub fn
as_simd
<const LANES:
usize
>(&self) -> (&
[T]
, &[
Simd
<T, LANES>], &
[T]
)
where
Simd
<T, LANES>:
AsRef
<
[T; LANES]
>,
T:
SimdElement
,
LaneCount
<LANES>:
SupportedLaneCount
,
🔬
This is a nightly-only experimental API. (
portable_simd
#86656
)
source
pub fn
as_simd
<const LANES:
usize
>(&self) -> (&
[T]
, &[
Simd
<T, LANES>], &
[T]
)
where
Simd
<T, LANES>:
AsRef
<
[T; LANES]
>,
T:
SimdElement
,
LaneCount
<LANES>:
SupportedLaneCount
,
portable_simd
#86656
)
Split a slice into a prefix, a middle of aligned SIMD types, and a suffix.
This is a safe wrapper around
slice::align_to
, so has the same weak
postconditions as that method. You’re only assured that
self.len() == prefix.len() + middle.len() * LANES + suffix.len()
.
Notably, all of the following are possible:
prefix.len() >= LANES
.
middle.is_empty()
despite
self.len() >= 3 * LANES
.
suffix.len() >= LANES
.
That said, this is a safe method, so if you’re only writing safe code,
then this can at most cause incorrect logic, not unsoundness.
Panics
This will panic if the size of the SIMD type is different from
LANES
times that of the scalar.
At the time of writing, the trait restrictions on
Simd<T, LANES>
keeps
that from ever happening, as only power-of-two numbers of lanes are
supported. It’s possible that, in the future, those restrictions might
be lifted in a way that would make it possible to see panics from this
method for something like
LANES == 3
.
Examples
#![feature(portable_simd)]
use core::simd::SimdFloat;
let short = &[1, 2, 3];
let (prefix, middle, suffix) = short.as_simd::<4>();
assert_eq!(middle, []); // Not enough elements for anything in the middle
// They might be split in any possible way between prefix and suffix
let it = prefix.iter().chain(suffix).copied();
assert_eq!(it.collect::<Vec<_>>(), vec![1, 2, 3]);
fn basic_simd_sum(x: &[f32]) -> f32 {
use std::ops::Add;
use std::simd::f32x4;
let (prefix, middle, suffix) = x.as_simd();
let sums = f32x4::from_array([
prefix.iter().copied().sum(),
0.0,
0.0,
suffix.iter().copied().sum(),
let sums = middle.iter().copied().fold(sums, f32x4::add);
sums.reduce_sum()
let numbers: Vec<f32> = (1..101).map(|x| x as _).collect();
assert_eq!(basic_simd_sum(&numbers[1..99]), 4949.0);
Run
source
pub fn
as_simd_mut
<const LANES:
usize
>(
&mut self
) -> (&mut
[T]
, &mut [
Simd
<T, LANES>], &mut
[T]
)
where
Simd
<T, LANES>:
AsMut
<
[T; LANES]
>,
T:
SimdElement
,
LaneCount
<LANES>:
SupportedLaneCount
,
🔬
This is a nightly-only experimental API. (
portable_simd
#86656
)
source
pub fn
as_simd_mut
<const LANES:
usize
>(
&mut self
) -> (&mut
[T]
, &mut [
Simd
<T, LANES>], &mut
[T]
)
where
Simd
<T, LANES>:
AsMut
<
[T; LANES]
>,
T:
SimdElement
,
LaneCount
<LANES>:
SupportedLaneCount
,
portable_simd
#86656
)
Split a mutable slice into a mutable prefix, a middle of aligned SIMD types,
and a mutable suffix.
This is a safe wrapper around
slice::align_to_mut
, so has the same weak
postconditions as that method. You’re only assured that
self.len() == prefix.len() + middle.len() * LANES + suffix.len()
.
Notably, all of the following are possible:
prefix.len() >= LANES
.
middle.is_empty()
despite
self.len() >= 3 * LANES
.
suffix.len() >= LANES
.
That said, this is a safe method, so if you’re only writing safe code,
then this can at most cause incorrect logic, not unsoundness.
This is the mutable version of
slice::as_simd
; see that for examples.
Panics
This will panic if the size of the SIMD type is different from
LANES
times that of the scalar.
At the time of writing, the trait restrictions on
Simd<T, LANES>
keeps
that from ever happening, as only power-of-two numbers of lanes are
supported. It’s possible that, in the future, those restrictions might
be lifted in a way that would make it possible to see panics from this
method for something like
LANES == 3
.
source
pub fn
is_sorted
(&self) ->
bool
where
T:
PartialOrd
<T>,
🔬
This is a nightly-only experimental API. (
is_sorted
#53485
)
source
pub fn
is_sorted
(&self) ->
bool
where
T:
PartialOrd
<T>,
is_sorted
#53485
)
Checks if the elements of this slice are sorted.
That is, for each element
a
and its following element
b
,
a <= b
must hold. If the
slice yields exactly zero or one element,
true
is returned.
Note that if
Self::Item
is only
PartialOrd
, but not
Ord
, the above definition
implies that this function returns
false
if any two consecutive items are not
comparable.
Examples
#![feature(is_sorted)]
let empty: [i32; 0] = [];
assert!([1, 2, 2, 9].is_sorted());
assert!(![1, 3, 2, 4].is_sorted());
assert!([0].is_sorted());
assert!(empty.is_sorted());
assert!(![0.0, 1.0, f32::NAN].is_sorted());
Run
source
pub fn
is_sorted_by
<'a, F>(&'a self, compare: F) ->
bool
where
F:
FnMut
(
&'a T
,
&'a T
) ->
Option
<
Ordering
>,
🔬
This is a nightly-only experimental API. (
is_sorted
#53485
)
source
pub fn
is_sorted_by
<'a, F>(&'a self, compare: F) ->
bool
where
F:
FnMut
(
&'a T
,
&'a T
) ->
Option
<
Ordering
>,
is_sorted
#53485
)
Checks if the elements of this slice are sorted using the given comparator function.
Instead of using
PartialOrd::partial_cmp
, this function uses the given
compare
function to determine the ordering of two elements. Apart from that, it’s equivalent to
is_sorted
; see its documentation for more information.
source
pub fn
is_sorted_by_key
<'a, F, K>(&'a self, f: F) ->
bool
where
F:
FnMut
(
&'a T
) -> K,
K:
PartialOrd
<K>,
🔬
This is a nightly-only experimental API. (
is_sorted
#53485
)
source
pub fn
is_sorted_by_key
<'a, F, K>(&'a self, f: F) ->
bool
where
F:
FnMut
(
&'a T
) -> K,
K:
PartialOrd
<K>,
is_sorted
#53485
)
Checks if the elements of this slice are sorted using the given key extraction function.
Instead of comparing the slice’s elements directly, this function compares the keys of the
elements, as determined by
f
. Apart from that, it’s equivalent to
is_sorted
; see its
documentation for more information.
Examples
#![feature(is_sorted)]
assert!(["c", "bb", "aaa"].is_sorted_by_key(|s| s.len()));
assert!(![-2i32, -1, 0, 3].is_sorted_by_key(|n| n.abs()));
Run
1.52.0
·
source
pub fn
partition_point
<P>(&self, pred: P) ->
usize
where
P:
FnMut
(
&T
) ->
bool
,
1.52.0
·
source
pub fn
partition_point
<P>(&self, pred: P) ->
usize
where
P:
FnMut
(
&T
) ->
bool
,
Returns the index of the partition point according to the given predicate
(the index of the first element of the second partition).
The slice is assumed to be partitioned according to the given predicate.
This means that all elements for which the predicate returns true are at the start of the slice
and all elements for which the predicate returns false are at the end.
For example,
[7, 15, 3, 5, 4, 12, 6]
is partitioned under the predicate
x % 2 != 0
(all odd numbers are at the start, all even at the end).
If this slice is not partitioned, the returned result is unspecified and meaningless,
as this method performs a kind of binary search.
See also
binary_search
,
binary_search_by
, and
binary_search_by_key
.
Examples
let v = [1, 2, 3, 3, 5, 6, 7];
let i = v.partition_point(|&x| x < 5);
assert_eq!(i, 4);
assert!(v[..i].iter().all(|&x| x < 5));
assert!(v[i..].iter().all(|&x| !(x < 5)));
Run
If all elements of the slice match the predicate, including if the slice
is empty, then the length of the slice will be returned:
let a = [2, 4, 8];
assert_eq!(a.partition_point(|x| x < &100), a.len());
let a: [i32; 0] = [];
assert_eq!(a.partition_point(|x| x < &100), 0);
Run
If you want to insert an item to a sorted vector, while maintaining
sort order:
let mut s = vec![0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55];
let num = 42;
let idx = s.partition_point(|&x| x < num);
s.insert(idx, num);
assert_eq!(s, [0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 42, 55]);
Run
source
pub fn
take
<R, 'a>(self: &mut &'a
[T]
, range: R) ->
Option
<&'a
[T]
>
where
R:
OneSidedRange
<
usize
>,
🔬
This is a nightly-only experimental API. (
slice_take
#62280
)
source
pub fn
take
<R, 'a>(self: &mut &'a
[T]
, range: R) ->
Option
<&'a
[T]
>
where
R:
OneSidedRange
<
usize
>,
slice_take
#62280
)
Removes the subslice corresponding to the given range
and returns a reference to it.
Returns
None
and does not modify the slice if the given
range is out of bounds.
Note that this method only accepts one-sided ranges such as
2..
or
..6
, but not
2..6
.
Examples
Taking the first three elements of a slice:
#![feature(slice_take)]
let mut slice: &[_] = &['a', 'b', 'c', 'd'];
let mut first_three = slice.take(..3).unwrap();
assert_eq!(slice, &['d']);
assert_eq!(first_three, &['a', 'b', 'c']);
Run
Taking the last two elements of a slice:
#![feature(slice_take)]
let mut slice: &[_] = &['a', 'b', 'c', 'd'];
let mut tail = slice.take(2..).unwrap();
assert_eq!(slice, &['a', 'b']);
assert_eq!(tail, &['c', 'd']);
Run
Getting
None
when
range
is out of bounds:
#![feature(slice_take)]
let mut slice: &[_] = &['a', 'b', 'c', 'd'];
assert_eq!(None, slice.take(5..));
assert_eq!(None, slice.take(..5));
assert_eq!(None, slice.take(..=4));
let expected: &[char] = &['a', 'b', 'c', 'd'];
assert_eq!(Some(expected), slice.take(..4));
Run
source
pub fn
take_mut
<R, 'a>(self: &mut &'a mut
[T]
, range: R) ->
Option
<&'a mut
[T]
>
where
R:
OneSidedRange
<
usize
>,
🔬
This is a nightly-only experimental API. (
slice_take
#62280
)
source
pub fn
take_mut
<R, 'a>(self: &mut &'a mut
[T]
, range: R) ->
Option
<&'a mut
[T]
>
where
R:
OneSidedRange
<
usize
>,
slice_take
#62280
)
Removes the subslice corresponding to the given range
and returns a mutable reference to it.
Returns
None
and does not modify the slice if the given
range is out of bounds.
Note that this method only accepts one-sided ranges such as
2..
or
..6
, but not
2..6
.
Examples
Taking the first three elements of a slice:
#![feature(slice_take)]
let mut slice: &mut [_] = &mut ['a', 'b', 'c', 'd'];
let mut first_three = slice.take_mut(..3).unwrap();
assert_eq!(slice, &mut ['d']);
assert_eq!(first_three, &mut ['a', 'b', 'c']);
Run
Taking the last two elements of a slice:
#![feature(slice_take)]
let mut slice: &mut [_] = &mut ['a', 'b', 'c', 'd'];
let mut tail = slice.take_mut(2..).unwrap();
assert_eq!(slice, &mut ['a', 'b']);
assert_eq!(tail, &mut ['c', 'd']);
Run
Getting
None
when
range
is out of bounds:
#![feature(slice_take)]
let mut slice: &mut [_] = &mut ['a', 'b', 'c', 'd'];
assert_eq!(None, slice.take_mut(5..));
assert_eq!(None, slice.take_mut(..5));
assert_eq!(None, slice.take_mut(..=4));
let expected: &mut [_] = &mut ['a', 'b', 'c', 'd'];
assert_eq!(Some(expected), slice.take_mut(..4));
Run
source
pub fn
take_first
<'a>(self: &mut &'a
[T]
) ->
Option
<
&'a T
>
🔬
This is a nightly-only experimental API. (
slice_take
#62280
)
source
pub fn
take_first
<'a>(self: &mut &'a
[T]
) ->
Option
<
&'a T
>
slice_take
#62280
)
source
pub fn
take_first_mut
<'a>(self: &mut &'a mut
[T]
) ->
Option
<
&'a mut T
>
🔬
This is a nightly-only experimental API. (
slice_take
#62280
)
source
pub fn
take_first_mut
<'a>(self: &mut &'a mut
[T]
) ->
Option
<
&'a mut T
>
slice_take
#62280
)
Removes the first element of the slice and returns a mutable
reference to it.
Returns
None
if the slice is empty.
Examples
#![feature(slice_take)]
let mut slice: &mut [_] = &mut ['a', 'b', 'c'];
let first = slice.take_first_mut().unwrap();
*first = 'd';
assert_eq!(slice, &['b', 'c']);
assert_eq!(first, &'d');
Run
source
pub fn
take_last
<'a>(self: &mut &'a
[T]
) ->
Option
<
&'a T
>
🔬
This is a nightly-only experimental API. (
slice_take
#62280
)
source
pub fn
take_last
<'a>(self: &mut &'a
[T]
) ->
Option
<
&'a T
>
slice_take
#62280
)
source
pub fn
take_last_mut
<'a>(self: &mut &'a mut
[T]
) ->
Option
<
&'a mut T
>
🔬
This is a nightly-only experimental API. (
slice_take
#62280
)
source
pub fn
take_last_mut
<'a>(self: &mut &'a mut
[T]
) ->
Option
<
&'a mut T
>
slice_take
#62280
)
Removes the last element of the slice and returns a mutable
reference to it.
Returns
None
if the slice is empty.
Examples
#![feature(slice_take)]
let mut slice: &mut [_] = &mut ['a', 'b', 'c'];
let last = slice.take_last_mut().unwrap();
*last = 'd';
assert_eq!(slice, &['a', 'b']);
assert_eq!(last, &'d');
Run
source
pub unsafe fn
get_many_unchecked_mut
<const N:
usize
>(
&mut self,
indices: [
usize
;
N
]
) -> [
&mut T
;
N
]
🔬
This is a nightly-only experimental API. (
get_many_mut
#104642
)
source
pub unsafe fn
get_many_unchecked_mut
<const N:
usize
>(
&mut self,
indices: [
usize
;
N
]
) -> [
&mut T
;
N
]
get_many_mut
#104642
)
Returns mutable references to many indices at once, without doing any checks.
For a safe alternative see
get_many_mut
.
Safety
Calling this method with overlapping or out-of-bounds indices is
undefined behavior
even if the resulting references are not used.
Examples
#![feature(get_many_mut)]
let x = &mut [1, 2, 4];
unsafe {
let [a, b] = x.get_many_unchecked_mut([0, 2]);
*a *= 10;
*b *= 100;
assert_eq!(x, &[10, 2, 400]);
Run
source
pub fn
get_many_mut
<const N:
usize
>(
&mut self,
indices: [
usize
;
N
]
) ->
Result
<[
&mut T
;
N
],
GetManyMutError
<N>>
🔬
This is a nightly-only experimental API. (
get_many_mut
#104642
)
source
pub fn
get_many_mut
<const N:
usize
>(
&mut self,
indices: [
usize
;
N
]
) ->
Result
<[
&mut T
;
N
],
GetManyMutError
<N>>
get_many_mut
#104642
)
Returns mutable references to many indices at once.
Returns an error if any index is out-of-bounds, or if the same index was
passed more than once.
Examples
#![feature(get_many_mut)]
let v = &mut [1, 2, 3];
if let Ok([a, b]) = v.get_many_mut([0, 2]) {
*a = 413;
*b = 612;
assert_eq!(v, &[413, 2, 612]);
Run
source
pub fn
flatten
(&self) -> &
[T]
🔬
This is a nightly-only experimental API. (
slice_flatten
#95629
)
source
pub fn
flatten
(&self) -> &
[T]
slice_flatten
#95629
)
Takes a
&[[T; N]]
, and flattens it to a
&[T]
.
Panics
This panics if the length of the resulting slice would overflow a
usize
.
This is only possible when flattening a slice of arrays of zero-sized
types, and thus tends to be irrelevant in practice. If
size_of::<T>() > 0
, this will never panic.
Examples
#![feature(slice_flatten)]
assert_eq!([[1, 2, 3], [4, 5, 6]].flatten(), &[1, 2, 3, 4, 5, 6]);
assert_eq!(
[[1, 2, 3], [4, 5, 6]].flatten(),
[[1, 2], [3, 4], [5, 6]].flatten(),
let slice_of_empty_arrays: &[[i32; 0]] = &[[], [], [], [], []];
assert!(slice_of_empty_arrays.flatten().is_empty());
let empty_slice_of_arrays: &[[u32; 10]] = &[];
assert!(empty_slice_of_arrays.flatten().is_empty());
Run
source
pub fn
flatten_mut
(&mut self) -> &mut
[T]
🔬
This is a nightly-only experimental API. (
slice_flatten
#95629
)
source
pub fn
flatten_mut
(&mut self) -> &mut
[T]
slice_flatten
#95629
)
Takes a
&mut [[T; N]]
, and flattens it to a
&mut [T]
.
Panics
This panics if the length of the resulting slice would overflow a
usize
.
This is only possible when flattening a slice of arrays of zero-sized
types, and thus tends to be irrelevant in practice. If
size_of::<T>() > 0
, this will never panic.
Examples
#![feature(slice_flatten)]
fn add_5_to_all(slice: &mut [i32]) {
for i in slice {
*i += 5;
let mut array = [[1, 2, 3], [4, 5, 6], [7, 8, 9]];
add_5_to_all(array.flatten_mut());
assert_eq!(array, [[6, 7, 8], [9, 10, 11], [12, 13, 14]]);
Run
source
pub fn
sort
(&mut self)
where
T:
Ord
,
source
pub fn
sort
(&mut self)
where
T:
Ord
,
Sorts the slice.
This sort is stable (i.e., does not reorder equal elements) and
O
(
n
* log(
n
)) worst-case.
When applicable, unstable sorting is preferred because it is generally faster than stable
sorting and it doesn’t allocate auxiliary memory.
See
sort_unstable
.
Current implementation
The current algorithm is an adaptive, iterative merge sort inspired by
timsort
.
It is designed to be very fast in cases where the slice is nearly sorted, or consists of
two or more sorted sequences concatenated one after another.
Also, it allocates temporary storage half the size of
self
, but for short slices a
non-allocating insertion sort is used instead.
Examples
let mut v = [-5, 4, 1, -3, 2];
v.sort();
assert!(v == [-5, -3, 1, 2, 4]);
Run
source
pub fn
sort_by
<F>(&mut self, compare: F)
where
F:
FnMut
(
&T
,
&T
) ->
Ordering
,
source
pub fn
sort_by
<F>(&mut self, compare: F)
where
F:
FnMut
(
&T
,
&T
) ->
Ordering
,
Sorts the slice with a comparator function.
This sort is stable (i.e., does not reorder equal elements) and
O
(
n
* log(
n
)) worst-case.
The comparator function must define a total ordering for the elements in the slice. If
the ordering is not total, the order of the elements is unspecified. An order is a
total order if it is (for all
a
,
b
and
c
):
total and antisymmetric: exactly one of
a < b
,
a == b
or
a > b
is true, and
transitive,
a < b
and
b < c
implies
a < c
. The same must hold for both
==
and
>
.
For example, while
f64
doesn’t implement
Ord
because
NaN != NaN
, we can use
partial_cmp
as our sort function when we know the slice doesn’t contain a
NaN
.
let mut floats = [5f64, 4.0, 1.0, 3.0, 2.0];
floats.sort_by(|a, b| a.partial_cmp(b).unwrap());
assert_eq!(floats, [1.0, 2.0, 3.0, 4.0, 5.0]);
Run
When applicable, unstable sorting is preferred because it is generally faster than stable
sorting and it doesn’t allocate auxiliary memory.
See
sort_unstable_by
.
Current implementation
The current algorithm is an adaptive, iterative merge sort inspired by
timsort
.
It is designed to be very fast in cases where the slice is nearly sorted, or consists of
two or more sorted sequences concatenated one after another.
Also, it allocates temporary storage half the size of
self
, but for short slices a
non-allocating insertion sort is used instead.
Examples
let mut v = [5, 4, 1, 3, 2];
v.sort_by(|a, b| a.cmp(b));
assert!(v == [1, 2, 3, 4, 5]);
// reverse sorting
v.sort_by(|a, b| b.cmp(a));
assert!(v == [5, 4, 3, 2, 1]);
Run
1.7.0
·
source
pub fn
sort_by_key
<K, F>(&mut self, f: F)
where
F:
FnMut
(
&T
) -> K,
K:
Ord
,
1.7.0
·
source
pub fn
sort_by_key
<K, F>(&mut self, f: F)
where
F:
FnMut
(
&T
) -> K,
K:
Ord
,
Sorts the slice with a key extraction function.
This sort is stable (i.e., does not reorder equal elements) and
O
(
m
*
n
* log(
n
))
worst-case, where the key function is
O
(
m
).
For expensive key functions (e.g. functions that are not simple property accesses or
basic operations),
sort_by_cached_key
is likely to be
significantly faster, as it does not recompute element keys.
When applicable, unstable sorting is preferred because it is generally faster than stable
sorting and it doesn’t allocate auxiliary memory.
See
sort_unstable_by_key
.
Current implementation
The current algorithm is an adaptive, iterative merge sort inspired by
timsort
.
It is designed to be very fast in cases where the slice is nearly sorted, or consists of
two or more sorted sequences concatenated one after another.
Also, it allocates temporary storage half the size of
self
, but for short slices a
non-allocating insertion sort is used instead.
Examples
let mut v = [-5i32, 4, 1, -3, 2];
v.sort_by_key(|k| k.abs());
assert!(v == [1, 2, -3, 4, -5]);
Run
1.34.0
·
source
pub fn
sort_by_cached_key
<K, F>(&mut self, f: F)
where
F:
FnMut
(
&T
) -> K,
K:
Ord
,
1.34.0
·
source
pub fn
sort_by_cached_key
<K, F>(&mut self, f: F)
where
F:
FnMut
(
&T
) -> K,
K:
Ord
,
Sorts the slice with a key extraction function.
During sorting, the key function is called at most once per element, by using
temporary storage to remember the results of key evaluation.
The order of calls to the key function is unspecified and may change in future versions
of the standard library.
This sort is stable (i.e., does not reorder equal elements) and
O
(
m
*
n
+
n
* log(
n
))
worst-case, where the key function is
O
(
m
).
For simple key functions (e.g., functions that are property accesses or
basic operations),
sort_by_key
is likely to be
faster.
Current implementation
The current algorithm is based on
pattern-defeating quicksort
by Orson Peters,
which combines the fast average case of randomized quicksort with the fast worst case of
heapsort, while achieving linear time on slices with certain patterns. It uses some
randomization to avoid degenerate cases, but with a fixed seed to always provide
deterministic behavior.
In the worst case, the algorithm allocates temporary storage in a
Vec<(K, usize)>
the
length of the slice.
Examples
let mut v = [-5i32, 4, 32, -3, 2];
v.sort_by_cached_key(|k| k.to_string());
assert!(v == [-3, -5, 2, 32, 4]);
Run
source
pub fn
to_vec_in
<A>(&self, alloc: A) ->
Vec
<T, A>
where
A:
Allocator
,
T:
Clone
,
🔬
This is a nightly-only experimental API. (
allocator_api
#32838
)
source
pub fn
to_vec_in
<A>(&self, alloc: A) ->
Vec
<T, A>
where
A:
Allocator
,
T:
Clone
,
allocator_api
#32838
)
source
pub fn
concat
<Item>(&self) -> <
[T]
as
Concat
<Item>>::
Output
ⓘ
where
[T]
:
Concat
<Item>,
Item: ?
Sized
,
source
pub fn
concat
<Item>(&self) -> <
[T]
as
Concat
<Item>>::
Output
ⓘ
where
[T]
:
Concat
<Item>,
Item: ?
Sized
,
1.3.0
·
source
pub fn
join
<Separator>(
&self,
sep: Separator
) -> <
[T]
as
Join
<Separator>>::
Output
ⓘ
where
[T]
:
Join
<Separator>,
1.3.0
·
source
pub fn
join
<Separator>(
&self,
sep: Separator
) -> <
[T]
as
Join
<Separator>>::
Output
ⓘ
where
[T]
:
Join
<Separator>,
1.23.0
·
source
pub fn
to_ascii_uppercase
(&self) ->
Vec
<
u8
,
Global
>
ⓘ
1.23.0
·
source
pub fn
to_ascii_uppercase
(&self) ->
Vec
<
u8
,
Global
>
ⓘ
Returns a vector containing a copy of this slice where each byte
is mapped to its ASCII upper case equivalent.
ASCII letters ‘a’ to ‘z’ are mapped to ‘A’ to ‘Z’,
but non-ASCII letters are unchanged.
To uppercase the value in-place, use
make_ascii_uppercase
.
1.23.0
·
source
pub fn
to_ascii_lowercase
(&self) ->
Vec
<
u8
,
Global
>
ⓘ
1.23.0
·
source
pub fn
to_ascii_lowercase
(&self) ->
Vec
<
u8
,
Global
>
ⓘ
Returns a vector containing a copy of this slice where each byte
is mapped to its ASCII lower case equivalent.
ASCII letters ‘A’ to ‘Z’ are mapped to ‘a’ to ‘z’,
but non-ASCII letters are unchanged.
To lowercase the value in-place, use
make_ascii_lowercase
.
Trait Implementations
§
source
§
impl<T, A>
BorrowMut
<
[T]
> for
Vec
<T, A>
where
A:
Allocator
,
source
§
impl<T, A>
BorrowMut
<
[T]
> for
Vec
<T, A>
where
A:
Allocator
,
source
§
fn
borrow_mut
(&mut self) -> &mut
[T]
source
§
fn
borrow_mut
(&mut self) -> &mut
[T]
Mutably borrows from an owned value.
Read more
1.2.0
·
source
§
impl<'a, T, A>
Extend
<
&'a T
> for
Vec
<T, A>
where
T:
Copy
+ 'a,
A:
Allocator
+ 'a,
1.2.0
·
source
§
impl<'a, T, A>
Extend
<
&'a T
> for
Vec
<T, A>
where
T:
Copy
+ 'a,
A:
Allocator
+ 'a,
Extend implementation that copies elements out of references before pushing them onto the Vec.
This implementation is specialized for slice iterators, where it uses
copy_from_slice
to
append the entire slice at once.
source
§
fn
extend
<I>(&mut self, iter: I)
where
I:
IntoIterator
<Item =
&'a T
>,
source
§
fn
extend
<I>(&mut self, iter: I)
where
I:
IntoIterator
<Item =
&'a T
>,
Extends a collection with the contents of an iterator.
Read more
source
§
fn
extend_one
(&mut self, _:
&'a T
)
source
§
fn
extend_one
(&mut self, _:
&'a T
)
🔬
This is a nightly-only experimental API. (
extend_one
#72631
)
Extends a collection with exactly one element.
source
§
impl<T, A>
Extend
<T> for
Vec
<T, A>
where
A:
Allocator
,
source
§
impl<T, A>
Extend
<T> for
Vec
<T, A>
where
A:
Allocator
,
source
§
fn
extend
<I>(&mut self, iter: I)
where
I:
IntoIterator
<Item = T>,
source
§
fn
extend
<I>(&mut self, iter: I)
where
I:
IntoIterator
<Item = T>,
Extends a collection with the contents of an iterator.
Read more
source
§
fn
extend_one
(&mut self, item: T)
source
§
fn
extend_one
(&mut self, item: T)
🔬
This is a nightly-only experimental API. (
extend_one
#72631
)
Extends a collection with exactly one element.
1.14.0
·
source
§
impl<'a, T>
From
<
Cow
<'a,
[T]
>> for
Vec
<T,
Global
>
where
[T]
:
ToOwned
<Owned =
Vec
<T,
Global
>>,
1.14.0
·
source
§
impl<'a, T>
From
<
Cow
<'a,
[T]
>> for
Vec
<T,
Global
>
where
[T]
:
ToOwned
<Owned =
Vec
<T,
Global
>>,
source
§
fn
from
(s:
Cow
<'a,
[T]
>) ->
Vec
<T,
Global
>
source
§
fn
from
(s:
Cow
<'a,
[T]
>) ->
Vec
<T,
Global
>
Convert a clone-on-write slice into a vector.
If
s
already owns a
Vec<T>
, it will be returned directly.
If
s
is borrowing a slice, a new
Vec<T>
will be allocated and
filled by cloning
s
’s items into it.
Examples
let o: Cow<[i32]> = Cow::Owned(vec![1, 2, 3]);
let b: Cow<[i32]> = Cow::Borrowed(&[1, 2, 3]);
assert_eq!(Vec::from(o), Vec::from(b));
Run
1.20.0
·
source
§
impl<T, A>
From
<
Vec
<T, A>> for
Box
<
[T]
, A>
where
A:
Allocator
,
1.20.0
·
source
§
impl<T, A>
From
<
Vec
<T, A>> for
Box
<
[T]
, A>
where
A:
Allocator
,
source
§
fn
from
(v:
Vec
<T, A>) ->
Box
<
[T]
, A>
source
§
fn
from
(v:
Vec
<T, A>) ->
Box
<
[T]
, A>
Convert a vector into a boxed slice.
If
v
has excess capacity, its items will be moved into a
newly-allocated buffer with exactly the right capacity.
Examples
assert_eq!(Box::from(vec![1, 2, 3]), vec![1, 2, 3].into_boxed_slice());
Run
Any excess capacity is removed:
let mut vec = Vec::with_capacity(10);
vec.extend([1, 2, 3]);
assert_eq!(Box::from(vec), vec![1, 2, 3].into_boxed_slice());
Run
1.10.0
·
source
§
impl<T, A>
From
<
VecDeque
<T, A>> for
Vec
<T, A>
where
A:
Allocator
,
1.10.0
·
source
§
impl<T, A>
From
<
VecDeque
<T, A>> for
Vec
<T, A>
where
A:
Allocator
,
source
§
fn
from
(other:
VecDeque
<T, A>) ->
Vec
<T, A>
source
§
fn
from
(other:
VecDeque
<T, A>) ->
Vec
<T, A>
Turn a
VecDeque<T>
into a
Vec<T>
.
This never needs to re-allocate, but does need to do
O
(
n
) data movement if
the circular buffer doesn’t happen to be at the beginning of the allocation.
Examples
use std::collections::VecDeque;
// This one is *O*(1).
let deque: VecDeque<_> = (1..5).collect();
let ptr = deque.as_slices().0.as_ptr();
let vec = Vec::from(deque);
assert_eq!(vec, [1, 2, 3, 4]);
assert_eq!(vec.as_ptr(), ptr);
// This one needs data rearranging.
let mut deque: VecDeque<_> = (1..5).collect();
deque.push_front(9);
deque.push_front(8);
let ptr = deque.as_slices().1.as_ptr();
let vec = Vec::from(deque);
assert_eq!(vec, [8, 9, 1, 2, 3, 4]);
assert_eq!(vec.as_ptr(), ptr);
Run
source
§
impl<T>
FromIterator
<T> for
Vec
<T,
Global
>
source
§
impl<T>
FromIterator
<T> for
Vec
<T,
Global
>
source
§
impl<T, A>
Hash
for
Vec
<T, A>
where
T:
Hash
,
A:
Allocator
,
source
§
impl<T, A>
Hash
for
Vec
<T, A>
where
T:
Hash
,
A:
Allocator
,
The hash of a vector is the same as that of the corresponding slice,
as required by the
core::borrow::Borrow
implementation.
#![feature(build_hasher_simple_hash_one)]
use std::hash::BuildHasher;
let b = std::collections::hash_map::RandomState::new();
let v: Vec<u8> = vec![0xa8, 0x3c, 0x09];
let s: &[u8] = &[0xa8, 0x3c, 0x09];
assert_eq!(b.hash_one(v), b.hash_one(s));
Run
source
§
impl<'a, T, A>
IntoIterator
for &'a
Vec
<T, A>
where
A:
Allocator
,
source
§
impl<'a, T, A>
IntoIterator
for &'a
Vec
<T, A>
where
A:
Allocator
,
source
§
impl<'a, T, A>
IntoIterator
for &'a mut
Vec
<T, A>
where
A:
Allocator
,
source
§
impl<'a, T, A>
IntoIterator
for &'a mut
Vec
<T, A>
where
A:
Allocator
,
source
§
impl<T, A>
IntoIterator
for
Vec
<T, A>
where
A:
Allocator
,
source
§
impl<T, A>
IntoIterator
for
Vec
<T, A>
where
A:
Allocator
,
source
§
fn
into_iter
(self) -> <
Vec
<T, A> as
IntoIterator
>::
IntoIter
ⓘ
source
§
fn
into_iter
(self) -> <
Vec
<T, A> as
IntoIterator
>::
IntoIter
ⓘ
Creates a consuming iterator, that is, one that moves each value out of
the vector (from start to end). The vector cannot be used after calling
this.
Examples
let v = vec!["a".to_string(), "b".to_string()];
let mut v_iter = v.into_iter();
let first_element: Option<String> = v_iter.next();
assert_eq!(first_element, Some("a".to_string()));
assert_eq!(v_iter.next(), Some("b".to_string()));
assert_eq!(v_iter.next(), None);
Run
source
§
impl<T, A>
Ord
for
Vec
<T, A>
where
T:
Ord
,
A:
Allocator
,
source
§
impl<T, A>
Ord
for
Vec
<T, A>
where
T:
Ord
,
A:
Allocator
,
Implements ordering of vectors,
lexicographically
.
1.21.0
·
source
§
fn
max
(self, other: Self) -> Self
where
Self:
Sized
,
1.21.0
·
source
§
fn
max
(self, other: Self) -> Self
where
Self:
Sized
,
Compares and returns the maximum of two values.
Read more
source
§
impl<T, U, A>
PartialEq
<&
[U]
> for
Vec
<T, A>
where
A:
Allocator
,
T:
PartialEq
<U>,
source
§
impl<T, U, A>
PartialEq
<&
[U]
> for
Vec
<T, A>
where
A:
Allocator
,
T:
PartialEq
<U>,
source
§
impl<T, U, A, const N:
usize
>
PartialEq
<&
[U; N]
> for
Vec
<T, A>
where
A:
Allocator
,
T:
PartialEq
<U>,
source
§
impl<T, U, A, const N:
usize
>
PartialEq
<&
[U; N]
> for
Vec
<T, A>
where
A:
Allocator
,
T:
PartialEq
<U>,
source
§
impl<T, U, A>
PartialEq
<&mut
[U]
> for
Vec
<T, A>
where
A:
Allocator
,
T:
PartialEq
<U>,
source
§
impl<T, U, A>
PartialEq
<&mut
[U]
> for
Vec
<T, A>
where
A:
Allocator
,
T:
PartialEq
<U>,
1.48.0
·
source
§
impl<T, U, A>
PartialEq
<
[U]
> for
Vec
<T, A>
where
A:
Allocator
,
T:
PartialEq
<U>,
1.48.0
·
source
§
impl<T, U, A>
PartialEq
<
[U]
> for
Vec
<T, A>
where
A:
Allocator
,
T:
PartialEq
<U>,
source
§
impl<T, U, A, const N:
usize
>
PartialEq
<
[U; N]
> for
Vec
<T, A>
where
A:
Allocator
,
T:
PartialEq
<U>,
source
§
impl<T, U, A, const N:
usize
>
PartialEq
<
[U; N]
> for
Vec
<T, A>
where
A:
Allocator
,
T:
PartialEq
<U>,
1.46.0
·
source
§
impl<T, U, A>
PartialEq
<
Vec
<U, A>> for &
[T]
where
A:
Allocator
,
T:
PartialEq
<U>,
1.46.0
·
source
§
impl<T, U, A>
PartialEq
<
Vec
<U, A>> for &
[T]
where
A:
Allocator
,
T:
PartialEq
<U>,
1.46.0
·
source
§
impl<T, U, A>
PartialEq
<
Vec
<U, A>> for &mut
[T]
where
A:
Allocator
,
T:
PartialEq
<U>,
1.46.0
·
source
§
impl<T, U, A>
PartialEq
<
Vec
<U, A>> for &mut
[T]
where
A:
Allocator
,
T:
PartialEq
<U>,
1.48.0
·
source
§
impl<T, U, A>
PartialEq
<
Vec
<U, A>> for
[T]
where
A:
Allocator
,
T:
PartialEq
<U>,
1.48.0
·
source
§
impl<T, U, A>
PartialEq
<
Vec
<U, A>> for
[T]
where
A:
Allocator
,
T:
PartialEq
<U>,
source
§
impl<T, U, A>
PartialEq
<
Vec
<U, A>> for
Cow
<'_,
[T]
>
where
A:
Allocator
,
T:
PartialEq
<U> +
Clone
,
source
§
impl<T, U, A>
PartialEq
<
Vec
<U, A>> for
Cow
<'_,
[T]
>
where
A:
Allocator
,
T:
PartialEq
<U> +
Clone
,
1.17.0
·
source
§
impl<T, U, A>
PartialEq
<
Vec
<U, A>> for
VecDeque
<T, A>
where
A:
Allocator
,
T:
PartialEq
<U>,
1.17.0
·
source
§
impl<T, U, A>
PartialEq
<
Vec
<U, A>> for
VecDeque
<T, A>
where
A:
Allocator
,
T:
PartialEq
<U>,
source
§
impl<T, U, A1, A2>
PartialEq
<
Vec
<U, A2>> for
Vec
<T, A1>
where
A1:
Allocator
,
A2:
Allocator
,
T:
PartialEq
<U>,
source
§
impl<T, U, A1, A2>
PartialEq
<
Vec
<U, A2>> for
Vec
<T, A1>
where
A1:
Allocator
,
A2:
Allocator
,
T:
PartialEq
<U>,
source
§
impl<T, A>
PartialOrd
<
Vec
<T, A>> for
Vec
<T, A>
where
T:
PartialOrd
<T>,
A:
Allocator
,
source
§
impl<T, A>
PartialOrd
<
Vec
<T, A>> for
Vec
<T, A>
where
T:
PartialOrd
<T>,
A:
Allocator
,
Implements comparison of vectors,
lexicographically
.
source
§
fn
partial_cmp
(&self, other: &
Vec
<T, A>) ->
Option
<
Ordering
>
source
§
fn
partial_cmp
(&self, other: &
Vec
<T, A>) ->
Option
<
Ordering
>
This method returns an ordering between
self
and
other
values if one exists.
Read more
source
§
fn
lt
(&self, other:
&Rhs
) ->
bool
source
§
fn
lt
(&self, other:
&Rhs
) ->
bool
This method tests less than (for
self
and
other
) and is used by the
<
operator.
Read more
source
§
fn
le
(&self, other:
&Rhs
) ->
bool
source
§
fn
le
(&self, other:
&Rhs
) ->
bool
This method tests less than or equal to (for
self
and
other
) and is used by the
<=
operator.
Read more
1.48.0
·
source
§
impl<T, A, const N:
usize
>
TryFrom
<
Vec
<T, A>> for
[T; N]
where
A:
Allocator
,
1.48.0
·
source
§
impl<T, A, const N:
usize
>
TryFrom
<
Vec
<T, A>> for
[T; N]
where
A:
Allocator
,
source
§
fn
try_from
(vec:
Vec
<T, A>) ->
Result
<
[T; N]
,
Vec
<T, A>>
source
§
fn
try_from
(vec:
Vec
<T, A>) ->
Result
<
[T; N]
,
Vec
<T, A>>
Gets the entire contents of the
Vec<T>
as an array,
if its size exactly matches that of the requested array.
Examples
assert_eq!(vec![1, 2, 3].try_into(), Ok([1, 2, 3]));
assert_eq!(<Vec<i32>>::new().try_into(), Ok([]));
Run
If the length doesn’t match, the input comes back in
Err
:
let r: Result<[i32; 4], _> = (0..10).collect::<Vec<_>>().try_into();
assert_eq!(r, Err(vec![0, 1, 2, 3, 4, 5, 6, 7, 8, 9]));
Run
If you’re fine with just getting a prefix of the
Vec<T>
,
you can call
.truncate(N)
first.
let mut v = String::from("hello world").into_bytes();
v.sort();
v.truncate(2);
let [a, b]: [_; 2] = v.try_into().unwrap();
assert_eq!(a, b' ');
assert_eq!(b, b'd');
Run
1.66.0
·
source
§
impl<T, const N:
usize
>
TryFrom
<
Vec
<T,
Global
>> for
Box
<
[T; N]
,
Global
>
1.66.0
·
source
§
impl<T, const N:
usize
>
TryFrom
<
Vec
<T,
Global
>> for
Box
<
[T; N]
,
Global
>
source
§
fn
try_from
(
vec:
Vec
<T,
Global
>
) ->
Result
<
Box
<
[T; N]
,
Global
>, <
Box
<
[T; N]
,
Global
> as
TryFrom
<
Vec
<T,
Global
>>>::
Error
>
source
§
fn
try_from
(
vec:
Vec
<T,
Global
>
) ->
Result
<
Box
<
[T; N]
,
Global
>, <
Box
<
[T; N]
,
Global
> as
TryFrom
<
Vec
<T,
Global
>>>::
Error
>
Attempts to convert a
Vec<T>
into a
Box<[T; N]>
.
Like
Vec::into_boxed_slice
, this is in-place if
vec.capacity() == N
,
but will require a reallocation otherwise.
Errors
Returns the original
Vec<T>
in the
Err
variant if
boxed_slice.len()
does not equal
N
.
Examples
This can be used with
vec!
to create an array on the heap:
let state: Box<[f32; 100]> = vec![1.0; 100].try_into().unwrap();
assert_eq!(state.len(), 100);
Run
source
§
impl<A:
Allocator
>
Write
for
Vec
<
u8
, A>
source
§
impl<A:
Allocator
>
Write
for
Vec
<
u8
, A>
Write is implemented for
Vec<u8>
by appending to the vector.
The vector will grow as needed.
source
§
fn
write
(&mut self, buf: &[
u8
]) ->
Result
<
usize
>
source
§
fn
write
(&mut self, buf: &[
u8
]) ->
Result
<
usize
>
Write a buffer into this writer, returning how many bytes were written.
Read more
source
§
fn
is_write_vectored
(&self) ->
bool
source
§
fn
is_write_vectored
(&self) ->
bool
🔬
This is a nightly-only experimental API. (
can_vector
#69941
)
source
§
fn
write_all
(&mut self, buf: &[
u8
]) ->
Result
<
()
>
source
§
fn
write_all
(&mut self, buf: &[
u8
]) ->
Result
<
()
>
Attempts to write an entire buffer into this writer.
Read more
source
§
fn
flush
(&mut self) ->
Result
<
()
>
source
§
fn
flush
(&mut self) ->
Result
<
()
>
Flush this output stream, ensuring that all intermediately buffered
contents reach their destination.
Read more
source
§
fn
write_all_vectored
(&mut self, bufs: &mut [
IoSlice
<'_>]) ->
Result
<
()
>
source
§
fn
write_all_vectored
(&mut self, bufs: &mut [
IoSlice
<'_>]) ->
Result
<
()
>
🔬
This is a nightly-only experimental API. (
write_all_vectored
#70436
)
Attempts to write multiple buffers into this writer.
Read more
source
§
impl<T, A>
Eq
for
Vec
<T, A>
where
T:
Eq
,
A:
Allocator
,
Auto Trait Implementations
§
§
impl<T, A>
RefUnwindSafe
for
Vec
<T, A>
where
A:
RefUnwindSafe
,
T:
RefUnwindSafe
,
§
impl<T, A>
Send
for
Vec
<T, A>
where
A:
Send
,
T:
Send
,
§
impl<T, A>
Sync
for
Vec
<T, A>
where
A:
Sync
,
T:
Sync
,
§
impl<T, A>
Unpin
for
Vec
<T, A>
where
A:
Unpin
,
T:
Unpin
,
§
impl<T, A>
UnwindSafe
for
Vec
<T, A>
where
A:
UnwindSafe
,
T:
UnwindSafe
,