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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, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

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