logo
Course thumb

Unix Threads in C

Courses with this lesson

Introduction to semaphores in C

#include <pthread.h> #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <string.h> #include <semaphore.h> #define THREAD_NUM 4 sem_t semaphore; void* routine(void* args) { sem_wait(&semaphore); sleep(1); printf("Hello from thread %d\n", *(int*)args); sem_post(&semaphore); free(args); } int main(int argc, char *argv[]) { pthread_t th[THREAD_NUM]; sem_init(&semaphore, 0, 4); int i; for (i = 0; i < THREAD_NUM; i++) { int* a = malloc(sizeof(int)); *a = i; if (pthread_create(&th[i], NULL, &routine, a) != 0) { perror("Failed to create thread"); } } for (i = 0; i < THREAD_NUM; i++) { if (pthread_join(th[i], NULL) != 0) { perror("Failed to join thread"); } } sem_destroy(&semaphore); return 0; }