Convert.ChangeType Method (Object, Type) (System)

.NET Framework Class Library

Convert..::.ChangeType Method (Object, Type)

Returns an object of the specified type and whose value is equivalent to the specified object.

Namespace: System
Assembly: mscorlib (in mscorlib.dll)

Syntax

Visual Basic (Declaration)

Public Shared Function ChangeType ( _
    value As Object, _
    conversionType As Type _
) As Object

Visual Basic (Usage)

Dim value As Object
Dim conversionType As Type
Dim returnValue As Object

returnValue = Convert.ChangeType(value, _
    conversionType)

public static Object ChangeType(
    Object value,
    Type conversionType
)

Visual C++

public:
static Object^ ChangeType(
    Object^ value, 
    Type^ conversionType
)

JScript

public static function ChangeType(
    value : Object, 
    conversionType : Type
) : Object

Parameters

value: Type: System..::.Object
An object that implements the IConvertible interface.

conversionType: Type: System..::.Type
The type of object to return.

Return Value

Type: System..::.Object
An object whose type is conversionType and whose value is equivalent to value.
-or-
A null reference (Nothing in Visual Basic), if value is nullNothingnullptra null reference (Nothing in Visual Basic) and conversionType is not a value type.

Exceptions

Exception	Condition
InvalidCastException	This conversion is not supported. -or- value is nullNothingnullptra null reference (Nothing in Visual Basic) and conversionType is a value type. -or- value does not implement the IConvertible interface.
FormatException	value is not in a format recognized by conversionType.
OverflowException	value represents a number that is out of the range of conversionType.
ArgumentNullException	conversionType is nullNothingnullptra null reference (Nothing in Visual Basic).

Remarks

ChangeType is a general-purpose conversion method that converts the object specified by value to conversionType. The value parameter can be an object of any type, and conversionType can also be a Type object that represents any base or custom type. For the conversion to succeed, value must implement the IConvertible interface, because the method simply wraps a call to an appropriate IConvertible method. The method requires that conversion of value to conversionType be supported.

This method uses the current thread's culture for the conversion.

Examples

The following example illustrates the use of the ChangeType method.

Visual Basic

Imports System

Public Class ChangeTypeTest

    Public Shared Sub Main()
        Dim d As [Double] = - 2.345
        Dim i As Integer = CInt(Convert.ChangeType(d, GetType(Integer)))

        Console.WriteLine("The double value {0} when converted to an int becomes {1}", d, i)
        Dim s As String = "12/12/98"
        Dim dt As DateTime = CType(Convert.ChangeType(s, GetType(DateTime)), DateTime)

        Console.WriteLine("The string value {0} when converted to a Date becomes {1}", s, dt)
    End Sub 'Main
End Class 'ChangeTypeTest

using System;

public class ChangeTypeTest {
    public static void Main() {

        Double d = -2.345;
        int i = (int)Convert.ChangeType(d, typeof(int));

        Console.WriteLine("The double value {0} when converted to an int becomes {1}", d, i);

        string s = "12/12/98";
        DateTime dt = (DateTime)Convert.ChangeType(s, typeof(DateTime));

        Console.WriteLine("The string value {0} when converted to a Date becomes {1}", s, dt);        
    }
}

Visual C++

using namespace System;

int main()
{
   Double d = -2.345;
   int i =  *safe_cast<Int32^>(Convert::ChangeType( d, int::typeid ));
   Console::WriteLine( "The double value {0} when converted to an int becomes {1}", d, i );
   String^ s = "12/12/98";
   DateTime dt =  *safe_cast<DateTime^>(Convert::ChangeType( s, DateTime::typeid ));
   Console::WriteLine( "The string value {0} when converted to a Date becomes {1}", s, dt );
}

JScript

import System;

public class ChangeTypeTest {
    public static function Main() {

        var d : Double = -2.345;
        var i : Int32 = Int32(Convert.ChangeType(d, Int32));

        Console.WriteLine("The double value {0} when converted to an int becomes {1}", d, i);

        var s : String = "12/12/98";
        var dt : DateTime = DateTime(Convert.ChangeType(s, DateTime));

        Console.WriteLine("The string value {0} when converted to a Date becomes {1}", s, dt);        
    }
}

Platforms

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Version Information

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0

Reference