/*

Simple example of running an arbitrary number of threads.
For example::

    $ gcc -pthread n_threads.c -o n_threads
    $ ./n_threads 10
    Hello this is thread 0: i=0
    Hello this is thread 0: i=1
    Hello this is thread 0: i=2
    Hello this is thread 0: i=3
    Hello this is thread 0: i=4
    Hello this is thread 0: i=5
    Hello this is thread 0: i=6
    Hello this is thread 0: i=7
    ...

*/

#include <assert.h>
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>

void *run_thread(void *argument) {
    int *p = argument;

    for (int i = 0; i < 42; i++) {
        printf("Hello this is thread %d: i=%d\n", *p, i);
    }
    return NULL;
}

int main(int argc, char *argv[]) {
    if (argc != 2) {
        fprintf(stderr, "Usage: %s <n-threads>\n", argv[0]);
        return 1;
    }

    int n_threads = strtol(argv[1], NULL, 0);
    assert(0 < n_threads && n_threads < 100);

    pthread_t thread_id[n_threads];
    int argument[n_threads];

    for (int i = 0; i < n_threads; i++) {
        argument[i] = i;
        pthread_create(&thread_id[i], NULL, run_thread, &argument[i]);
    }

    // Wait for the threads to finish
    for (int i = 0; i < n_threads; i++) {
        pthread_join(thread_id[i], NULL);
    }

    return 0;
}