###### (This is the legacy documentation for stable SDL2, the current stable version; [SDL3](https://wiki.libsdl.org/SDL3/) is the current development version.) # SDL_SemTryWait See if a semaphore has a positive value and decrement it if it does. ## Syntax ```c int SDL_SemTryWait(SDL_sem * 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 2.0.0. ## Related Functions * [SDL_CreateSemaphore](SDL_CreateSemaphore) * [SDL_DestroySemaphore](SDL_DestroySemaphore) * [SDL_SemPost](SDL_SemPost) * [SDL_SemValue](SDL_SemValue) * [SDL_SemWait](SDL_SemWait) * [SDL_SemWaitTimeout](SDL_SemWaitTimeout) ---- [CategoryAPI](CategoryAPI)