Wait for a thread to finish.
Defined in <SDL3/SDL_thread.h>
| thread | the SDL_Thread pointer that was returned from the SDL_CreateThread() call that started this thread |
| status | pointer to an integer that will receive the value returned from the thread function by its 'return', or NULL to not receive such value back. |
Threads that haven't been detached will remain (as a "zombie") until this function cleans them up. Not doing so is a resource leak.
Once a thread has been cleaned up through this function, the SDL_Thread that references it becomes invalid and should not be referenced again. As such, only one thread may call SDL_WaitThread() on another.
The return code for the thread function is placed in the area pointed to by status, if status is not NULL.
You may not wait on a thread that has been used in a call to SDL_DetachThread(). Use either that function or this one, but not both, or behavior is undefined.
It is safe to pass a NULL thread to this function; it is a no-op.
Note that the thread pointer is freed by this function and is not valid afterward.
This function is available since SDL 3.0.0.
#include <SDL3/SDL.h>
// Very simple thread - counts 0 to 9 delaying 50ms between increments
static int TestThread(void *ptr)
{
int cnt;
for (cnt = 0; cnt < 10; ++cnt) {
SDL_Log("Thread counter: %d\n", cnt);
SDL_Delay(50);
}
// Return the final value to the SDL_WaitThread function above
return cnt;
}
int main(int argc, char *argv[])
{
SDL_Thread *thread;
int threadReturnValue;
SDL_Log("Simple SDL_CreateThread test:");
// Simply create a thread
thread = SDL_CreateThread(TestThread, "TestThread", (void *)NULL);
if (NULL == thread) {
SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "SDL_CreateThread failed: %s\n", SDL_GetError());
} else {
// Wait for the thread to complete. The thread functions return code will
// be placed in the "threadReturnValue" variable when it completes.
//
SDL_WaitThread(thread, &threadReturnValue);
SDL_Log("Thread returned value: %d\n", threadReturnValue);
}
return 0;
}