A version of this page is also available for

Windows Embedded CE 6.0 R3


This function performs an atomic comparison of the specified parameter values and exchanges the values based on the outcome of the comparison. More than one thread cannot use the same variable simultaneously.

If you are exchanging pointer values, this function supersedes InterlockedCompareExchange.


PVOID InterlockedCompareExchangePointer(
  PVOID* Destination,
  PVOID ExChange,
  PVOID Comperand


  • Destination
    [in/out] Pointer to the pointer to the destination value. The sign is ignored.
  • ExChange
    [in] Exchange value. The sign is ignored.
  • Comperand
    [in] Value to compare to Destination. The sign is ignored.

Return Value

Initial value of the destination.


The interlocked functions provide a simple mechanism for synchronizing access to a variable that is shared by multiple threads. The threads of different processes can use this mechanism, if the variable is in shared memory.

InterlockedCompareExchange performs an atomic comparison of the Destination ** value with the Comperand ** value. If the Destination ** value is equal to the Comperand ** value, the ExChange ** value is stored in the address specified by Destination. Otherwise, no operation is performed.


Header winbase.h
Library coredll.lib
Windows Embedded CE Windows CE .NET 4.0 and later
Windows Mobile Windows Mobile Version 5.0 and later

See Also


Synchronization Functions