pthread_join的第二个参数怎么使用？

[fibbery]

请给一个具体的例子和输出。谢谢。

[rzsheng]

http://www.ibm.com/developerworks/cn/linux/thread/posix_threadapi/part4/

[mengjfu]

#include <stdio.h>

#include <pthread.h>

void thread1(char s[])


{
printf("This is a pthread1.\n");
printf("%s\n",s);
pthread_exit("hello"); //结束线程，返回一个值。
}

/**************main function ****************/

int main(void)


{
pthread_t id1;
void *a1;
int i,ret1;
char s1[]="This is first thread!";
ret1=pthread_create(&id1,NULL,(void *) thread1,s1);

if(ret1!=0){
printf ("Create pthread1 error!\n");
exit (1);
}
pthread_join(id1,&a1);

printf("%s\n",(char*)a1);

return (0);

}

[mengjfu]

输出：this is a pthread1.
this is first thread!
hello first!

其中和hello first即为返回输出。

[mengjfu]

输出：this is a pthread1.
this is first thread!
hello first!

其中hello first即为返回输出。

[猫已经找不回了]

飞飞，apue上有例子的啊。

[猫已经找不回了]

这是一个分离线程跟普通线程的对比例子，上面有pthread_join的用法对比，你看看吧

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

void* task1(void*);
void* task2(void*);

void usr();

int p1,p2;

int main()
{
   p1=0;
   p2=0;
    usr();
    getchar();
    return 1;
}

void usr()
{
	pthread_t pid1, pid2;
    	pthread_attr_t attr;
   	 void *p;
	 int ret=0;
	pthread_attr_init(&attr);
   	 pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
   	 pthread_create(&pid1, &attr, task1, NULL);
   	 ret=pthread_join(pid1, &p);
   	 printf("after pthread1:ret=%d,p=%d\n", ret,(int)p);
    pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE);
	if(p2==0)
   	{	pthread_create(&pid2, &attr, task2, NULL);
  		p2=1;
	}

}


void* task1(void *arg1)
{
    printf("task1\n");
    pthread_exit( (void *)1);
}

void* task2(void *arg2)
{
    int i=0;
    printf("thread2 begin.\n");
    //pthread_detach(pthread_self());
   for(i=0;i<100;i++)
   {
        sleep(2);
        printf("At thread2: i is %d\n",i);
        usr();
   }
    pthread_exit((void *)2);
}