Public Class Complex : Implements IConvertible
Private x, y As Double
Public Sub New(ByVal x As Double, ByVal y As Double)
Me.x = x
Me.y = y
End Sub
Function GetDoubleValue() As Double
Return Math.Sqrt((x * x + y * y))
End Function
' The remaining code provides IConvertible method implementations.
Public Function GetTypeCode() As TypeCode Implements IConvertible.GetTypeCode
Return TypeCode.Object
End Function
Function ToBoolean(ByVal provider As IFormatProvider) As Boolean _
Implements IConvertible.ToBoolean
Return x <> 0 OrElse y <> 0
End Function
Function ToByte(ByVal provider As IFormatProvider) As Byte Implements IConvertible.ToByte
Return Convert.ToByte(GetDoubleValue())
End Function
Function ToChar(ByVal provider As IFormatProvider) As Char Implements IConvertible.ToChar
Return Convert.ToChar(GetDoubleValue())
End Function
Function ToDateTime(ByVal provider As IFormatProvider) As DateTime Implements IConvertible.ToDateTime
Return Convert.ToDateTime(GetDoubleValue())
End Function
Function ToDecimal(ByVal provider As IFormatProvider) As Decimal Implements IConvertible.ToDecimal
Return Convert.ToDecimal(GetDoubleValue())
End Function
Function ToDouble(ByVal provider As IFormatProvider) As Double Implements IConvertible.ToDouble
Return GetDoubleValue()
End Function
Function ToInt16(ByVal provider As IFormatProvider) As Short Implements IConvertible.ToInt16
Return Convert.ToInt16(GetDoubleValue())
End Function
Function ToInt32(ByVal provider As IFormatProvider) As Integer Implements IConvertible.ToInt32
Return Convert.ToInt32(GetDoubleValue())
End Function
Function ToInt64(ByVal provider As IFormatProvider) As Long Implements IConvertible.ToInt64
Return Convert.ToInt64(GetDoubleValue())
End Function
Function ToSByte(ByVal provider As IFormatProvider) As SByte Implements IConvertible.ToSByte
Return Convert.ToSByte(GetDoubleValue())
End Function
Function ToSingle(ByVal provider As IFormatProvider) As Single Implements IConvertible.ToSingle
Return Convert.ToSingle(GetDoubleValue())
End Function
Overloads Function ToString(ByVal provider As IFormatProvider) As String Implements IConvertible.ToString
Return String.Format("({0}, {1})", x, y)
End Function
Function ToType(ByVal conversionType As Type, ByVal provider As IFormatProvider) As Object Implements IConvertible.ToType
Return Convert.ChangeType(GetDoubleValue(), conversionType)
End Function
Function ToUInt16(ByVal provider As IFormatProvider) As UInt16 Implements IConvertible.ToUInt16
Return Convert.ToUInt16(GetDoubleValue())
End Function
Function ToUInt32(ByVal provider As IFormatProvider) As UInt32 Implements IConvertible.ToUInt32
Return Convert.ToUInt32(GetDoubleValue())
End Function
Function ToUInt64(ByVal provider As IFormatProvider) As UInt64 Implements IConvertible.ToUInt64
Return Convert.ToUInt64(GetDoubleValue())
End Function
End Class
Public Module Example
Sub Main()
Dim testComplex As New Complex(4, 7)
WriteObjectInfo(testComplex)
WriteObjectInfo(Convert.ToBoolean(testComplex))
WriteObjectInfo(Convert.ToDecimal(testComplex))
WriteObjectInfo(Convert.ToString(testComplex))
End Sub
Sub WriteObjectInfo(ByVal testObject As Object)
Dim typeCode As TypeCode = Type.GetTypeCode(testObject.GetType())
Select Case typeCode
Case typeCode.Boolean
Console.WriteLine("Boolean: {0}", testObject)
Case typeCode.Double
Console.WriteLine("Double: {0}", testObject)
Case Else
Console.WriteLine("{0}: {1}", typeCode.ToString(), testObject)
End Select
End Sub
End Module
This interface provides methods to convert the value of an instance of an implementing type to a common language runtime type that has an equivalent value. The common language runtime types are
Boolean
,
SByte
,
Byte
,
Int16
,
UInt16
,
Int32
,
UInt32
,
Int64
,
UInt64
,
Single
,
Double
,
Decimal
,
DateTime
,
Char
, and
String
.
If there is no meaningful conversion to a common language runtime type, then a particular interface method implementation throws
InvalidCastException
. For example, if this interface is implemented on a Boolean type, the implementation of the
ToDateTime
method throws an exception because there is no meaningful
DateTime
equivalent to a Boolean type.
The common language runtime typically exposes the
IConvertible
interface through the
Convert
class. The common language runtime also uses the
IConvertible
interface internally, in explicit interface implementations, to simplify the code used to support conversions in the
Convert
class and basic common language runtime types.
In addition to the
IConvertible
interface, the .NET Framework provides classes called type converters for converting user-defined data types to other data types. For more information, see the
Generalized Type Conversion
topic.
Notes to Implementers
If you implement the
IConvertible
interface, your implementation will be called automatically by the
ChangeType(Object, Type)
method if the
Object
parameter is an instance of your implementing type and the
Type
parameter is a common language runtime type.
Most conversion methods have a parameter of type
IFormatProvider
that represents either the current culture (
CurrentCulture
) or a specific culture. For the most part, the
IConvertible
implementations of the base types ignore this parameter. However, you can choose whether to use it in your code.
