How do I use condition variables with mutex in C?

How do I use condition variables with mutex in C?

To use condition variables with mutex in C, you need to include the pthread library. First, initialize a mutex and a condition variable.

Can you show me a simple example?

Sure! Here's a basic example:

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

pthread_mutex_t mutex;
pthread_cond_t cond;
int shared_data = 0;

void* producer(void* arg) {
    pthread_mutex_lock(&mutex);
    shared_data = 1;
    pthread_cond_signal(&cond);
    pthread_mutex_unlock(&mutex);
    return NULL;
}

void* consumer(void* arg) {
    pthread_mutex_lock(&mutex);
    while (shared_data == 0) {
        pthread_cond_wait(&cond, &mutex);
    }
    printf("Data received: %d\n", shared_data);
    pthread_mutex_unlock(&mutex);
    return NULL;
}

int main() {
    pthread_t prod, cons;
    pthread_mutex_init(&mutex, NULL);
    pthread_cond_init(&cond, NULL);
    pthread_create(&prod, NULL, producer, NULL);
    pthread_create(&cons, NULL, consumer, NULL);
    pthread_join(prod, NULL);
    pthread_join(cons, NULL);
    pthread_mutex_destroy(&mutex);
    pthread_cond_destroy(&cond);
    return 0;
}

What happens if I forget to unlock the mutex?

If you forget to unlock the mutex, it can lead to a deadlock situation where other threads are unable to acquire the mutex, causing your program to hang.