pthread_mutex.c

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

pthread_mutex_t lock;

void *thread_f(void *d)
{
    int *ptr = d;

    while (1) {
        sleep(1);

        pthread_mutex_lock(&lock);

        (*ptr) ++;

        pthread_mutex_unlock(&lock);
    }
}


int main()
{
    int t = 4;
    pthread_t tid;
    pthread_attr_t attr;
    int ret;

    ret = pthread_attr_init(&attr);
    if (ret < 0) {
        return -1;
    }

    ret = pthread_mutex_init(&lock, NULL);
    if (ret < 0) {
        return -1;
    }

    ret = pthread_create(&tid, &attr, thread_f, &t);
    if (ret < 0) {
        return -1;
    }

    while (1) {

        pthread_mutex_lock(&lock);

        printf("t value %d\n", t);

        pthread_mutex_unlock(&lock);
        sleep(1);
    }

    return 0;
};