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static void FreeHGlobal(IntPtr hglobal);
[System.Security.SecurityCritical]
public static void FreeHGlobal (IntPtr hglobal);
public static void FreeHGlobal (IntPtr hglobal);
[<System.Security.SecurityCritical>]
static member FreeHGlobal : nativeint -> unit
static member FreeHGlobal : nativeint -> unit
Public Shared Sub FreeHGlobal (hglobal As IntPtr)
Parameters
Examples
The following example demonstrates calling the
FreeHGlobal
method. This code example is part of a larger example provided for the
Marshal
class.
// Demonstrate how to call GlobalAlloc and
// GlobalFree using the Marshal class.
IntPtr hglobal = Marshal::AllocHGlobal(100);
Marshal::FreeHGlobal(hglobal);
// Demonstrate how to call GlobalAlloc and
// GlobalFree using the Marshal class.
IntPtr hglobal = Marshal.AllocHGlobal(100);
Marshal.FreeHGlobal(hglobal);
' Demonstrate how to call GlobalAlloc and
' GlobalFree using the Marshal class.
Dim hglobal As IntPtr = Marshal.AllocHGlobal(100)
Marshal.FreeHGlobal(hglobal)
The following example demonstrates how to convert the contents of a managed
String
class to unmanaged memory and then dispose of the unmanaged memory when done.
using namespace System;
using namespace System::Runtime::InteropServices;
#include <iostream> // for printf
int main()
// Create a managed string.
String^ managedString = "Hello unmanaged world (from the managed world).";
// Marshal the managed string to unmanaged memory.
char* stringPointer = (char*) Marshal::StringToHGlobalAnsi(managedString ).ToPointer();
printf("stringPointer = %s\n", stringPointer);
// Always free the unmanaged string.
Marshal::FreeHGlobal(IntPtr(stringPointer));
return 0;
using System;
using System.Runtime.InteropServices;
using System.Threading;
class MainFunction
static void Main()
Console.WriteLine("\nStringToGlobalAnsi\n");
// Create a managed string.
String managedString = "I am a managed String";
Console.WriteLine("1) managedString = " + managedString);
// Marshal the managed string to unmanaged memory.
IntPtr stringPointer = (IntPtr)Marshal.StringToHGlobalAnsi(managedString);
Console.WriteLine("2) stringPointer = {0}", stringPointer);
// Get the string back from unmanaged memory.
String RetrievedString = Marshal.PtrToStringAnsi(stringPointer);
Console.WriteLine("3) Retrieved from unmanaged memory = " + RetrievedString);
// Always free the unmanaged string.
Marshal.FreeHGlobal(stringPointer);
// IntPtr handle value is still the same:
Console.WriteLine("4) stringPointer = " + stringPointer);
// However, the data may be cleared after the memory is freed, depending on whether the memory allocated to stringPointer
// has been reclaimed or not. Uncommenting the following line (Thread.Sleep(1000)) increases the likelihood of the memory being reclaimed.
// Thread.Sleep(1000);
String RetrievedString2 = Marshal.PtrToStringAnsi(stringPointer);
Console.WriteLine("5) RetrievedString2 = " + RetrievedString2);
Remarks
You can use
FreeHGlobal
to free any memory from the global heap allocated by
AllocHGlobal
,
ReAllocHGlobal
, or any equivalent unmanaged API method. If the
hglobal
parameter is
IntPtr.Zero
the method does nothing.
FreeHGlobal
exposes the
LocalFree
function from Kernel32.DLL, which frees all bytes so that you can no longer use the memory pointed to by
hglobal
.
In addition to
FreeHGlobal
, the
Marshal
class provides two other memory-deallocation API methods:
DestroyStructure
and
FreeCoTaskMem
.
