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Interlocked.Exchange<T> Method (T%, T)

Sets a variable of the specified type T to a specified value and returns the original value, as an atomic operation.

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

public static T Exchange<T>(
	ref T location1,
	T value
where T : class

Type Parameters


The type to be used for location1 and value. This type must be a reference type.


Type: T%
The variable to set to the specified value. This is a reference parameter (ref in C#, ByRef in Visual Basic).
Type: T
The value to which the location1 parameter is set.

Return Value

Type: T
The original value of location1.


The address of location1 is a null pointer.

This method only supports reference types. There are overloads of the Exchange method for the value types Int32, Int64, IntPtr, Single, and Double, but there is no support for other value types.


This method overload is preferable to the Exchange(Object, Object) method overload, because the latter requires the destination object to be accessed late-bound.

.NET Framework

Supported in: 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

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.