Why printf is not working with multple threads in c?

Question

In the code below I create 8 threads and each of those prints a string and its id. However, I don't see any printf output in stdout from PrintHello function. One strange thing that is happening is that if run the main using debugger (CLion) printf indeed outputs the intended output. I actually suspect that no code inside PrintHello function is run, not just printf. What could be causing this?

Also according to this answer printf is thread-safe so it shouldn't be an issue of different threads competing for stdout.

This is the code (it as adapted from these slides):

#include <stdio.h>
#include <stdlib.h>
#include <ntsid.h>
#include <pthread.h>
#include <unistd.h>

#define BAD_EXIT 1
#define NUM_TASKS 8

char * messages[NUM_TASKS];

void * PrintHello(void * taskIdPtr) {
    int taskId;
    sleep(1);
    taskId = *((int *) taskIdPtr);
    printf("Task id = %d, message = %s\n", taskId, messages[taskId]);
    free(taskIdPtr);
    pthread_exit(NULL);
}
int main(int argc, char ** argv) {
    pthread_t threads[NUM_TASKS];
    int * taskIdPtr;
    int rc, t;
    messages[0] = "English: Hello World!";
    messages[1] = "French: Bonjour, le monde!";
    messages[2] = "Spanish: Hola al mundo";
    messages[3] = "Klingon: Nuq neH!";
    messages[4] = "German: Guten Tag, Welt!";
    messages[5] = "Russian: Zdravstvytye, mir!";
    messages[6] = "Japan: Sekai e konnichiwa!";
    messages[7] = "Latin: Orbis, te saluto!";

    for(t = 0; t < NUM_TASKS; t++) {
        taskIdPtr = (int *) malloc(sizeof(int));
        *taskIdPtr = t;
        printf("Creating thread %d\n", t);
        rc = pthread_create(&threads[t], NULL, PrintHello, (void *) taskIdPtr);
        if(rc) {
            perror("Error :");
            exit(BAD_EXIT);
        }
    }
    return 0;
}

Answer 1

The main process is exiting before the newly created threads gets executed. So you should wait for the threads created using pthread_join.

As per the man page of pthread_join

int pthread_join(pthread_t thread, void **retval);

The pthread_join() function waits for the thread specified by thread to terminate. If that thread has already terminated, then pthread_join() returns immediately. The thread specified by thread must be joinable.