Interlocked.CompareExchange Method (Int64, Int64, Int64)

Compares two 64-bit signed integers for equality and, if they are equal, replaces one of the values.

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

public static long CompareExchange (
	ref long location1,
	long value,
	long comparand
public static long CompareExchange (
	/** @ref */ long location1, 
	long value, 
	long comparand
Not applicable.



The destination, whose value is compared with comparand and possibly replaced.


The value that replaces the destination value if the comparison results in equality.


The value that is compared to the value at location1.

Return Value

The original value in location1.

Exception typeCondition


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 compare and exchange operations are performed as an atomic operation. The return value of CompareExchange is the original value in location1, whether or not the exchange takes place.

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

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0

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