A simple thread program

#include
#include
#include
#include

void *thread_function(void *arg);

char message[] = "Hello World";

int main()
{
 int res;
 pthread_t a_thread;
 void *thread_result;
 res = pthread_create(&a_thread,NULL,thread_function,(void *)message);
 if (res != 0)
 {
  perror("Thread creation failed");
  exit(EXIT_FAILURE);
 }
 printf("Waiting for thread to finish....\n");
 res = pthread_join(a_thread,&thread_result);
 if (res != 0)
 {
  perror("Thread join failed");
  exit(EXIT_FAILURE);
 }
 printf("Thread joined,it returned %s\n",(char *)thread_result);
 printf("Message is now %s\n",message);
 exit(EXIT_SUCCESS);
}

void *thread_function(void *arg)
{
 printf("thread_function is running. Argument was %s\n",(char *)arg);
 sleep(3);
 strcpy(message,"Bye");
 pthread_exit("Thank you for the CPU time");
}

 

 

 

 

int pthread_create(pthread_t *newthread,pthread_attr_t *attr,void *thread_func(void *),void *arg)
函数产生新线程，newthread返回pthread号，新线程从thread_func(void *)函数
开始运行，成功返回0，失败返回错误码。注意linux内核无法确定新线程和主线程谁先运行。

 

 

如果pthread_create 创建线程成功了，就会有两个线程在运行。原先的线程（main）继续执行pthread_create后面的代码，而新线程开始执行thread_function函数。