#include
#include
#include
#define THREAD_NUMBER 3//线程个数
#define REPEAT_NUMBER 5
#define DELAY_TIME_LEVELS 10.0
void *thrd_func(void *arg)//线程函数
{
int thrd_num = (int)arg ;
int delay_time = 0 ;
int count = 0 ;
printf("thread %d is starting\n", thrd_num) ;
for (count = 0; count < REPEAT_NUMBER; count++)//每个线程完成五次任务
{
delay_time = (int)(rand() * DELAY_TIME_LEVELS/(RAND_MAX)) + 1;//产生随机时间
sleep(delay_time) ;
printf("\tThread %d:job %d delay = %d\n",
thrd_num, count, delay_time) ;
}
printf("thread %d finished\n", thrd_num) ;
pthread_exit(NULL) ;
}
int main()
{
pthread_t thread[THREAD_NUMBER] ;
int no = 0, res ;
void *thrd_ret ;
srand(time(NULL)) ;//产生随机种子
for(no = 0; no < THREAD_NUMBER; no++)
{
res = pthread_create(&thread[no], NULL, thrd_func, (void *)no) ;//创建线程
if (res != 0)
{
printf("create thread %d failed\n", no) ;
exit(res) ;
}
}
printf("create threads success\n waiting for threads to finish...\n") ;
for (no = 0; no < THREAD_NUMBER; no++)
{
res = pthread_join(thread[no], &thrd_ret) ;//等待线程结束
if (!res)
{
printf("thread %d joined\n", no) ;
}
else
{
printf("thread %d joined failed", no) ;
}
}
exit(0) ;
}
为什么首先输出的是这段create threads success waiting for threads to finish...，不是应该先调用了线程函数么，为什么首先输出的不是thread %d is starting，本人小白，求大侠指点，感谢？
调用线程函数不等于先执行它，线程调用是异步的，执行顺序是随机的。
线程和主进程 是时间片占用CPU的， 也就是说这两个线程之间不是同步的，不分先后顺序执行
多线程序就没有顺序的概念了，除非加代码让它们有序运行，这就又回到单线程了