###### (This is the documentation for SDL3, which is under heavy development and the API is changing! [SDL2](https://wiki.libsdl.org/SDL2/) is the current stable version!) # SDL_TryWaitSemaphore See if a semaphore has a positive value and decrement it if it does. ## Syntax ```c int SDL_TryWaitSemaphore(SDL_Semaphore *sem); ``` ## Function Parameters | | | | ----------- | ------------------------ | | **sem** | the semaphore to wait on | ## Return Value Returns 0 if the wait succeeds, [`SDL_MUTEX_TIMEDOUT`](SDL_MUTEX_TIMEDOUT) if the wait would block, or a negative error code on failure; call [SDL_GetError](SDL_GetError)() for more information. ## Remarks This function checks to see if the semaphore pointed to by `sem` has a positive value and atomically decrements the semaphore value if it does. If the semaphore doesn't have a positive value, the function immediately returns [SDL_MUTEX_TIMEDOUT](SDL_MUTEX_TIMEDOUT). ## Version This function is available since SDL 3.0.0. ## Related Functions * [SDL_PostSemaphore](SDL_PostSemaphore) * [SDL_WaitSemaphore](SDL_WaitSemaphore) * [SDL_WaitSemaphoreTimeout](SDL_WaitSemaphoreTimeout) ---- [CategoryAPI](CategoryAPI)