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

Compares two instances of the specified reference type T for equality and, if they are equal, replaces one of them.

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

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

Type Parameters


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


Type: T%
The destination whose value is compared with comparand and possibly replaced. This is a reference parameter (ref in C#, ByRef in Visual Basic).
Type: T
The value that replaces the destination value if the comparison results in equality.
Type: T
The value that is compared to the value at location1.

Return Value

Type: T
The original value in location1.


The address of location1 is a null pointer.

If comparand and the value in location1 are equal, then value is stored in location1. Otherwise, no operation is performed. The comparison and the exchange are performed as an atomic operation. The return value of this method is the original value in location1, whether or not the exchange takes place.

This method only supports reference types. In Silverlight there are overloads of the CompareExchange method for the value types Int32 and Int64, but there is no support for other value types.


Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Xbox 360, Windows Phone OS 7.0

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

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