# SDL_IsMainThread Return whether this is the main thread. ## Header File Defined in [](https://github.com/libsdl-org/SDL/blob/main/include/SDL3/SDL_init.h) ## Syntax ```c bool SDL_IsMainThread(void); ``` ## Return Value (bool) Returns true if this thread is the main thread, or false otherwise. ## Remarks On Apple platforms, the main thread is the thread that runs your program's main() entry point. On other platforms, the main thread is the one that calls [SDL_Init](SDL_Init)([SDL_INIT_VIDEO](SDL_INIT_VIDEO)), which should usually be the one that runs your program's main() entry point. If you are using the main callbacks, [SDL_AppInit](SDL_AppInit)(), [SDL_AppIterate](SDL_AppIterate)(), and [SDL_AppQuit](SDL_AppQuit)() are all called on the main thread. ## Thread Safety It is safe to call this function from any thread. ## Version This function is available since SDL 3.2.0. ## See Also - [SDL_RunOnMainThread](SDL_RunOnMainThread) ---- [CategoryAPI](CategoryAPI), [CategoryAPIFunction](CategoryAPIFunction), [CategoryInit](CategoryInit)