please dont rip this site Prev Next

ReleaseSemaphore info  Overview  Group

The ReleaseSemaphore function increases the count of the specified semaphore object by a specified amount.

BOOL ReleaseSemaphore(

    HANDLE hSemaphore,

// handle of the semaphore object

    LONG lReleaseCount,

// amount to add to current count

    LPLONG lpPreviousCount 

// address of previous count



Identifies the semaphore object. The CreateSemaphore or OpenSemaphore function returns this handle.

Windows NT: This handle must have SEMAPHORE_MODIFY_STATE access. For more information, see Interprocess Synchronization Objects.

Specifies the amount by which the semaphore object’s current count is to be increased. The value must be greater than zero. If the specified amount would cause the semaphore’s count to exceed the maximum count that was specified when the semaphore was created, the count is not changed and the function returns FALSE.
Points to a 32-bit variable to receive the previous count for the semaphore. This parameter can be NULL if the previous count is not required.

Return Values

If the function succeeds, the return value is nonzero.

If the function fails, the return value is zero. To get extended error information, call GetLastError.


The state of a semaphore object is signaled when its count is greater than zero and nonsignaled when its count is equal to zero. The process that calls the CreateSemaphore function specifies the semaphore’s initial count. Each time a waiting thread is released because of the semaphore’s signaled state, the count of the semaphore is decreased by one.

Typically, an application uses a semaphore to limit the number of threads using a resource. Before a thread uses the resource, it specifies the semaphore handle in a call to one of the wait functions. When the wait function returns, it decreases the semaphore’s count by one. When the thread has finished using the resource, it calls ReleaseSemaphore to increase the semaphore’s count by one.

Another use of ReleaseSemaphore is during an application’s initialization. The application can create a semaphore with an initial count of zero. This sets the semaphore’s state to nonsignaled and blocks all threads from accessing the protected resource. When the application finishes its initialization, it uses ReleaseSemaphore to increase the count to its maximum value, to permit normal access to the protected resource.

See Also

CreateSemaphore, OpenSemaphore


file: /Techref/os/win/api/win32/func/src/f73_19.htm, 4KB, , updated: 2000/4/7 12:19, local time: 2024/7/20 08:35,

 ©2024 These pages are served without commercial sponsorship. (No popup ads, etc...).Bandwidth abuse increases hosting cost forcing sponsorship or shutdown. This server aggressively defends against automated copying for any reason including offline viewing, duplication, etc... Please respect this requirement and DO NOT RIP THIS SITE. Questions?
Please DO link to this page! Digg it! / MAKE!

<A HREF=""> ReleaseSemaphore</A>

After you find an appropriate page, you are invited to your to this massmind site! (posts will be visible only to you before review) Just type a nice message (short messages are blocked as spam) in the box and press the Post button. (HTML welcomed, but not the <A tag: Instead, use the link box to link to another page. A tutorial is available Members can login to post directly, become page editors, and be credited for their posts.

Link? Put it here: 
if you want a response, please enter your email address: 
Attn spammers: All posts are reviewed before being made visible to anyone other than the poster.
Did you find what you needed?

  PICList 2024 contributors:
o List host: MIT, Site host, Top posters @none found
- Page Editors: James Newton, David Cary, and YOU!
* Roman Black of Black Robotics donates from sales of Linistep stepper controller kits.
* Ashley Roll of Digital Nemesis donates from sales of RCL-1 RS232 to TTL converters.
* Monthly Subscribers: Gregg Rew. on-going support is MOST appreciated!
* Contributors: Richard Seriani, Sr.

Welcome to!