In C programming, if using return in main function, the whole process will terminate. To only let main thread gone, and keep other threads live, you can use thrd_exit in main function. Check following code:#include #include #include intprint_thread(void *s){ thrd_detach(thrd_current()); for (size_t i = 0; i < 5; i++) { sleep(1); printf("i=%zu\n", i); } thrd_exit(0);}intmain(void){ thrd_t tid; if (thrd_success != thrd_create(&tid, print_thread, NULL)) { fprintf(stderr, "Create thread err...