linux编程实现三个线程ABC，并让它们顺次打印自己的ID，使用信号量

#include <pthread.h> #include <stdio.h> #include <semaphore.h> #include <errno.h> #include <stdlib.h> #include <unistd.h> static sem_t sem1,sem2,sem3; int global = 0; #define MAX 15 void *t1_exe(void *arg){ while (global<MAX) { sem_wait(&sem1) ; printf("In thread1 %lu\n",pthread_self()); global++; sem_post(&sem2); sleep(1); } } void *t2_exe(void *arg){ while (global<MAX) { sem_wait(&sem2) ; printf("In thread2 %lu\n",pthread_self()); global++; sem_post(&sem3); sleep(1); } } void *t3_exe(void *arg){ while (global<MAX) { sem_wait(&sem3) ; printf("In thread3 %lu\n",pthread_self()); global++; sem_post(&sem1); sleep(1); } } void main() { int i; pthread_t t_a[3]; sem_init(&sem1,0,1); sem_init(&sem2,0,0); sem_init(&sem3,0,0); pthread_create(&t_a[0],NULL,t1_exe,(void *)NULL);/*´´½¨*/ pthread_create(&t_a[1],NULL,t2_exe,(void *)NULL); pthread_create(&t_a[2],NULL,t3_exe,(void *)NULL); for(i=0;i<3;i++) pthread_join(t_a[i],NULL); sem_destroy(&sem1); sem_destroy(&sem2); sem_destroy(&sem3); return ; }