hilos.c

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

int valor = 0;
pthread_mutex_t mutex;

void* decrementarValor(void* parametro) {
	int i;
	for (i = 0; i < 1000; i++) {
		pthread_mutex_lock(&mutex);
		valor--;
		pthread_mutex_unlock(&mutex);
	}

	return 0;
}


int main(int argc, char **argv) {
	pthread_mutex_init(&mutex, NULL);

	pthread_t unHilo;
	pthread_create(&unHilo, 0, decrementarValor, 0);

	pthread_t otroHilo;
	pthread_create(&otroHilo, 0, decrementarValor, 0);

	pthread_join(unHilo, NULL);
	pthread_join(otroHilo, NULL);

	printf("%d", valor);

	return 0;
}