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Interlocked.CompareExchange Method (IntPtr%, IntPtr, IntPtr)

Compares two platform-specific handles or pointers for equality and, if they are equal, replaces one of them.

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

public static IntPtr CompareExchange(
	ref IntPtr location1,
	IntPtr value,
	IntPtr comparand


Type: System.IntPtr%
The destination IntPtr, whose value is compared with the value of comparand and possibly replaced by value.
Type: System.IntPtr
The IntPtr that replaces the destination value if the comparison results in equality.
Type: System.IntPtr
The IntPtr that is compared to the value at location1.

Return Value

Type: System.IntPtr
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 compare and exchange operations 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.


IntPtr is a platform-specific type.

.NET Framework

Supported in: 4, 3.5, 3.0, 2.0

.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.