线程互斥锁

mutex.c

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

int i=0;
pthread_mutex_t mutex;

void *f(void *buf)
{
 char b[]="change";
 printf("buf in the created pthread:%s\n",(char *)buf);
 strncpy(buf, b, 6);
 

 pthread_mutex_lock(&mutex);//加锁
 i = 2;
 printf("in pthread i=: %d\n",i);
 sleep(1);
 i = i+1;
 printf("in pthread second i=: %d\n",i);
 pthread_mutex_unlock(&mutex);//解锁

 

 pthread_exit("ok,the join to exit is success!");
}

int main()
{ 
 pthread_t tid;
 void *result;
 char buf[]="test for the pthread\n";
 if((pthread_mutex_init(&mutex, NULL)) == -1)
 {
  printf("init failure");
 }
 pthread_create(&tid, NULL, f, (void *)buf);//需要放在创建锁的后面，否则有问题

 pthread_mutex_lock(&mutex);//加锁

 i = 1;
 printf("in main i=: %d\n",i);
 sleep(1);
 i = i+1;
 printf("in main second i=: %d\n",i);
 pthread_mutex_unlock(&mutex);//解锁

 printf("buf in main:%s\n",buf);
 pthread_join(tid, &result);
 printf("the return is : %s\n",(char *)result);
 return 0;
}