訊號量semaphore

sem_post 計數器加一
sem_wait 計數器為遞減 為0的時候等待

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

void *thread_function(void *arg);
sem_t bin_sem;

#define WORK_SIZE 1024
char work_area[WORK_SIZE];
int main(){
    int res;
    pthread_t a_thread;
    void *thread_result;

    res = sem_init(&bin_sem,0,0);
    if(res != 0 ){
        perror("Semaphore initailization failed!");
        exit(EXIT_FAILURE);
    }   

    res = pthread_create(&a_thread,NULL,thread_function,NULL);
    if(res != 0){ 
        perror("Thread creation failed!");
        exit(EXIT_FAILURE);
    }   
    printf("Input some text,Enter 'end' to finish\n");
    while(strncmp("end",work_area,3)!=0){
        fgets(work_area,WORK_SIZE,stdin);
        printf("%s\n",work_area);
        sem_post(&bin_sem);
    }   

    pthread_join(a_thread,&thread_result);                                                                                         
    sem_destroy(&bin_sem);
}

void *thread_function(void *arg){
    sem_wait(&bin_sem);
    while(strncmp("end",work_area,3) != 0){ 
        printf("You input %d characters\n",strlen(work_area) -1);
        sem_wait(&bin_sem);
    }   
    pthread_exit(NULL);
}

互斥量

不好用 沒搞懂