InterlockedDecrement function (winnt.h)

Article
10/13/2021

Decrements (decreases by one) the value of the specified 32-bit variable as an atomic operation.

To operate on 64-bit values, use the InterlockedDecrement64 function.

Syntax

LONG InterlockedDecrement(
  [in, out] LONG volatile *Addend
);

Parameters

[in, out] Addend

A pointer to the variable to be decremented.

Return value

The function returns the resulting decremented value.

Remarks

The variable pointed to by the Addend parameter must be aligned on a 32-bit boundary; otherwise, this function will behave unpredictably on multiprocessor x86 systems and any non-x86 systems. See _aligned_malloc.

The interlocked functions provide a simple mechanism for synchronizing access to a variable that is shared by multiple threads. This function is atomic with respect to calls to other interlocked functions.

This function is implemented using a compiler intrinsic where possible. For more information, see the WinBase.h header file and _InterlockedDecrement.

This function generates a full memory barrier (or fence) to ensure that memory operations are completed in order.

Itanium-based systems: For performance-critical applications, use InterlockedDecrementAcquire or InterlockedDecrementRelease instead.

Note This function is supported on Windows RT-based systems.

Requirements

Requirement	Value
Minimum supported client	Windows XP [desktop apps \| UWP apps]
Minimum supported server	Windows Server 2003 [desktop apps \| UWP apps]
Target Platform	Windows
Header	winnt.h (include Windows.h)
Library	Kernel32.lib
DLL	Kernel32.dll