SDL_CreateThread

Use this function to create a new thread.

Syntax

SDL_Thread* SDL_CreateThread(SDL_ThreadFunction fn,
                             const char*        name,
                             void*              data)

Function Parameters

Return Value

Returns an opaque pointer to the new thread object on success, NULL if the new thread could not be created; call SDL_GetError() for more information.

Code Examples

#include <stdio.h>
#include <SDL_thread.h>
#include <SDL_timer.h>

int TestThread( void *ptr );

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
        {
           SDL_WaitThread( thread, &threadReturnValue);
           printf("\nThread returned value:%d", threadReturnValue);
        }

        return 1;
}

// Very simple thread - counts 0 to 9 delaying 50ms between increments
int TestThread( void *ptr )
{
        int        cnt;

        for(cnt=0;cnt<10;cnt++)
        {
                printf( "\nThread counter: %d", cnt);
                SDL_Delay(50);
        }

        return cnt;
}

Output:

Simple SDL_CreateThread test:
Thread counter: 0
Thread counter: 1
Thread counter: 2
Thread counter: 3
Thread counter: 4
Thread counter: 5
Thread counter: 6
Thread counter: 7
Thread counter: 8
Thread counter: 9
Thread returned value:10

Remarks

SDL_CreateThread() creates a new thread of execution that shares all of its parent's global memory, signal handlers, file descriptors, etc, and runs the function fn, passing it the void pointer data. The thread quits when fn returns.

The function prototype for fn is:

• int SDL_ThreadFunction(void* data)

  • where its parameter is:

  data	what was passed as data to SDL_CreateThread()

There are no requirements for thread naming conventions, so long as the string is null-terminated UTF-8, but these guidelines are helpful in choosing a name:

• http://stackoverflow.com/questions/149932/naming-conventions-for-threads

If a system imposes requirements, SDL will try to munge the string for it (truncate, etc), but the original string contents will be available from SDL_GetThreadName().

Related Functions

• SDL_WaitThread

CategoryAPI, CategoryThread