#include <stdio.h>
#include <pthread.h>
#include <error.h>

#define NTHREADS 4
static int k = 0;

struct thread_info{
    pthread_t thread_id;
    pthread_mutex_t lock;
    int x;
    int a[10];
};

void* fkt(void* arg){
    struct thread_info* tinfo = (struct thread_info*) arg;

    if(pthread_mutex_lock(&tinfo->lock)) perror("mutex_lock");

    printf("THREAD %d with argument %dn", (int) tinfo->thread_id, tinfo->x);

    tinfo->a[k] = tinfo->x * tinfo->x;
    k++;

    if(pthread_mutex_unlock(&tinfo->lock)) perror("mutex_unlock");

    pthread_exit(NULL);
}

int main(){
    struct thread_info* tinfo = NULL;

    tinfo->x = 5;

    if(pthread_mutex_init(&tinfo->lock, NULL)) perror("mutex_init");

    for(int i = 0; i < NTHREADS; i++){
        if(pthread_create(&tinfo[i].thread_id, NULL, &fkt, &tinfo)) perror("pthread_create");
    }
    for(int i = 0; i < NTHREADS; i++){
        if(pthread_join(tinfo[i].thread_id, NULL)) perror("pthread_join");
        printf("THREAD JOINED: %dn", (int) tinfo->thread_id);
    }
    for(int i = 0; i < 10; i++){
        printf("[%d]t", tinfo->a[i]);
    }
    printf("n");

    if(pthread_mutex_destroy(&tinfo->lock)) perror("mutex_destroy");

    return 0;
}