c/c++ 線程的使用基礎教程

#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER; /*初始化互斥鎖*/
pthread_cond_t cond = PTHREAD_COND_INITIALIZER;  //初始化條件變量 

void *thread1(void *);
void *thread2(void *);

int i=1;
int main(void)
{
        pthread_t t_a;
        pthread_t t_b;
        pthread_create(&t_a,NULL,thread1,(void *)NULL);/*創建進程t_a*/
        pthread_create(&t_b,NULL,thread2,(void *)NULL); /*創建進程t_b*/
        pthread_join(t_b, NULL);/*等待進程t_b結束*/
        pthread_mutex_destroy(&mutex);
        pthread_cond_destroy(&cond);
         exit(0);
}

void *thread1(void *junk)
{
        for(i=1;i<=9;i++)
        {
             pthread_mutex_lock(&mutex);//
             if(i%3==0)
                 pthread_cond_signal(&cond);/*條件改變，發送信號，通知t_b進程*/
              else       
                  printf("thead1:%d\n",i);
              pthread_mutex_unlock(&mutex);//*解鎖互斥量*/
              printf("Up Unlock Mutex\n");      
              sleep(1.5);
        }

}

void *thread2(void *junk)
{
        while(i<9)
        {
              pthread_mutex_lock(&mutex);

            if(i%3!=0)
                   pthread_cond_wait(&cond,&mutex);/*等待*/
            printf("thread2:%d\n",i);
            pthread_mutex_unlock(&mutex);
            printf("Down Ulock Mutex\n");

            sleep(1);
                }

}

#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER; /*初始化互斥鎖*/
//pthread_cond_t cond = PTHREAD_COND_INITIALIZER;  //初始化條件變量 

void *thread1(void *);
void *thread2(void *);

int i=1;
int main(void)
{
        pthread_t t_a;
        pthread_t t_b;
        pthread_create(&t_a,NULL,thread1,(void *)NULL);/*創建進程t_a*/
        pthread_create(&t_b,NULL,thread2,(void *)NULL); /*創建進程t_b*/
        pthread_join(t_b, NULL);/*等待進程t_b結束*/
        pthread_mutex_destroy(&mutex);
  //      pthread_cond_destroy(&cond);
         exit(0);
}

void *thread1(void *junk)
{
        while(i<9)
 {
  i++;
             pthread_mutex_lock(&mutex);//
    //             pthread_cond_signal(&cond);/*條件改變，發送信號，通知t_b進程*/
                  printf("thead1:%d\n",i);
              pthread_mutex_unlock(&mutex);//*解鎖互斥量*/
              sleep(1);
        }

}

void *thread2(void *junk)
{
        while(i<9)
        {
              pthread_mutex_lock(&mutex);
i++;
            printf("thread2:%d\n",i);
            pthread_mutex_unlock(&mutex);

            sleep(1);
                }

}

第一例子中 有條件變量，即設置一個線程間的變量，當thread1 條件符合後可通過 pthread_cond_signal(&cond);/*條件改變，發送信號，通知t_b進程*/ 發送信號，這樣在 pthread_cond_wait(&cond,&mutex);/*等待*/的 thread2 就被喚醒。實現了線程間的調用。而第二個例子，是去掉條件變量，直接兩個線程是獨立的。