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Interlocked.Exchange Method (Object, Object)

Sets an object to a specified value and returns a reference to the original object, as an atomic operation.

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

public static Object Exchange(
	ref Object location1,
	Object value


Type: System.Object

The variable to set to the specified value.

Type: System.Object

The value to which the location1 parameter is set.

Return Value

Type: System.Object
The original value of location1.


The address of location1 is a null pointer.

Beginning with .NET Framework version 2.0, the Exchange<T>(T, T) method overload provides a type-safe alternative for reference types.

The following code example shows the syntax for using Exchange with any reference type object.

using System;
using System.Threading;

class AtomicTest
    static void Main()
        AtomicExchange atomicExchange = new AtomicExchange();
        Thread firstThread = 
            new Thread(new ThreadStart(atomicExchange.Switch));

class AtomicExchange
    class SomeType{}

    // To use Interlocked.Exchange, someType1  
    // must be declared as type Object. 
    object   someType1;
    SomeType someType2;

    public AtomicExchange() 
        someType1 = new SomeType();
        someType2 = new SomeType();

    public void Switch()
        someType2 = (SomeType)Interlocked.Exchange(
            ref someType1, (object)someType2);

.NET Framework

Supported in: 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

.NET for Windows Store apps

Supported in: Windows 8

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone Silverlight 8.1, Windows Phone Silverlight 8

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

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

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