InterlockedExchange function (winnt.h)

Sets a 32-bit variable to the specified value as an atomic operation.

To operate on a pointer variable, use the InterlockedExchangePointer function.

To operate on a 16-bit variable, use the InterlockedExchange16 function.

To operate on a 64-bit variable, use the InterlockedExchange64 function.

Syntax

LONG InterlockedExchange(
  [in, out] LONG volatile *Target,
  [in]      LONG          Value
);

Parameters

[in, out] Target

A pointer to the value to be exchanged. The function sets this variable to Value, and returns its prior value.

[in] Value

The value to be exchanged with the value pointed to by Target.

Return value

The function returns the initial value of the Target parameter.

Remarks

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 _InterlockedExchange.

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 InterlockedExchangeAcquire 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

See also

Interlocked Variable Access

InterlockedCompareExchange

InterlockedExchange

InterlockedExchange16

InterlockedExchange16Acquire

InterlockedExchange16NoFence

InterlockedExchange64

InterlockedExchange8

InterlockedExchangeAcquire

InterlockedExchangeAcquire64

InterlockedExchangeAdd

InterlockedExchangeAdd64

InterlockedExchangeAddAcquire

">InterlockedExchangeAddAcquire64

InterlockedExchangeAddNoFence

InterlockedExchangeAddNoFence64

<a href="/previous-versions/windows/desktop/legacy/ms683605(v=vs.85)".InterlockedExchangeAddRelease

InterlockedExchangeAddRelease64

InterlockedExchangeNoFence

InterlockedExchangeNoFence64

InterlockedExchangePointer

InterlockedExchangePointerAcquire

InterlockedExchangePointerNoFence

InterlockedExchangeSubtract

Synchronization Functions