线程父子打印文本C语言

Question

I've wrote a program in which I create a thread in main that has a son who calls maFunction to show a text message . The problem is that when I execute this it doesn't work and I don't understand why . Any idea is welcomed . Thank you very much .

#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
void * maFonction (void * val) {
    char * chaine = (char *) val;
    printf ("text received: %s\n", chaine);
}

int main(void) {
    pthread_t leThread;
    int ret = pthread_create (&leThread, NULL, maFonction, "First program with Pthreads");
    if (ret != 0) {
        perror ("pthread_create");
        exit(EXIT_FAILURE) ;
    }
} 

Answer 1

Your program end execution before your thread start.

add pthread_join(leThread, NULL); at the end of main()

or add sleep(1); and don't forget to include <unistd.h> for sleep()

Answer 2

The issue is that your main function is immediately returning. When it returns, the C standard library then causes a process exit. The process exit kills both the main thread and any other threads. Hence, your sub-thread never gets a chance to start before the main thread has effectively killed it.

Add a sleep(1) just before the closing brace in main to delay the process exit a bit and you'll see your sub-thread's printf fire.

+1 to @Nick-s' answer: one ought to pthread_join in order to reap the sub-thread. However, leaving my answer here for its explanation.