#pragma section-numbers off
#pragma camelcase off

= SDL_WaitThread =
Use this function to wait for a thread to finish.

<<TableOfContents()>>

== Syntax ==
{{{#!highlight cpp
void SDL_WaitThread(SDL_Thread* thread,
                    int*        status)
}}}
== Function Parameters ==
||'''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. see [[#Remarks|Remarks]] for details ||

== Code Examples ==
{{{#!highlight cpp
#include <stdio.h>
#include "SDL_thread.h"
#include "SDL_timer.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) {
        printf("\nThread counter: %d", 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;

    printf("\nSimple SDL_CreateThread test:");

    // Simply create a thread
    thread = SDL_CreateThread(TestThread, "TestThread", (void *)NULL);

    if (NULL == thread) {
        printf("\nSDL_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);
        printf("\nThread returned value: %d", threadReturnValue);
    }

    return 0;
}
}}}

== Remarks ==

Wait for a thread to finish. 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.

== Related Functions ==
 . [[SDL_CreateThread]]
 . [[SDL_DetachThread]]

----
[[CategoryAPI]], [[CategoryThread]]