/* primo esempio di utilizzo dei semafori */
#include <stdio.h>
#include <pthread.h>
#include <semaphore.h>
sem_t mysem;

void *body(void *arg)
{
	int i,j;
sem_wait(&mysem); 
	for (j=0; j<40; j++) {
		
		for (i=0; i<1000000; i++); printf("%c",*(char *)arg); 	
		
	}
sem_post(&mysem);
	return NULL;
}

int main()
{
	pthread_t t1,t2,t3;  pthread_attr_t myattr; int err;

	sem_init(&mysem,0,1);
	pthread_attr_init(&myattr);
	err = pthread_create(&t1, &myattr, body, (void *)".");
	err = pthread_create(&t2, &myattr, body, (void *)"#");
	err = pthread_create(&t3, &myattr, body, (void *)"o");
	pthread_attr_destroy(&myattr);

	pthread_join(t1, NULL); pthread_join(t2, NULL); pthread_join(t3, NULL);

	printf("\n");
	return 0;
}