| Platform SDK: DLLs, Processes, and Threads |
The InterlockedDecrement function decrements (decreases by one) the value of the specified variable and checks the resulting value. The function prevents more than one thread from using the same variable simultaneously.
LONG InterlockedDecrement( LPLONG lpAddend // variable address );
Windows 98, Windows NT 4.0 and later: The return value is the resulting decremented value.
Windows 95, Windows NT 3.51 and earlier: If the result of the operation is zero, the return value is zero. If the result of the operation is less than zero, the return value is negative, but it is not necessarily equal to the result. If the result of the operation is greater than zero, the return value is positive, but it is not necessarily equal to the result.
The functions InterlockedDecrement, InterlockedCompareExchange, InterlockedExchange, InterlockedExchangeAdd, and InterlockedIncrement 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.
The variable pointed to by the lpAddend parameter must be aligned on a 32-bit boundary; otherwise, this function will fail on multiprocessor x86 systems and any non-x86 systems.
MAPI: For more information, see Syntax and Limitations for Win32 Functions Useful in MAPI Development.
Windows NT/2000: Requires Windows NT 3.1 or later.
Windows 95/98: Requires Windows 95 or later.
Header: Declared in Winbase.h; include Windows.h.
Library: Use Kernel32.lib.
Synchronization Overview, Synchronization Functions, Interlocked Variable Access, InterlockedCompareExchange, InterlockedExchange, InterlockedExchangeAdd, InterlockedIncrement