实用操作系统实验 子线程与主线程输出顺序（用C语言）

建立两个子线程thread1，thread2，要求thread1和thread2在主线程之前执行（thread1和thread2的顺序任意）
建立两个子线程thread1，thread2，要求thread1在前，thread2在后执行，（主线程的顺序任意）
建立两个子线程thread1，thread2，要求thread1在前，主线程其次，最后是thread2

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

void print_message_function (void *ptr);
int main()
{
     int tmp1, tmp2;
     void *retval;
     pthread_t thread1, thread2;
     char *message1 = "thread1";
     char *message2 = "thread2"; 
     int ret_thrd1, ret_thrd2; 
     ret_thrd1 = pthread_create(&thread1, NULL, (void *)&print_message_function, (void *) message1);
     ret_thrd2 = pthread_create(&thread2, NULL, (void *)&print_message_function, (void *) message2);
     // 线程创建成功，返回0,失败返回失败号
     if (ret_thrd1 != 0) {
         printf("线程1创建失败\n");
     } else {
         printf("线程1创建成功\n");
     } 
     if (ret_thrd2 != 0) {
         printf("线程2创建失败\n");
     } else {
         printf("线程2创建成功\n");
     } 
     //同样，pthread_join的返回值成功为0
     tmp1 = pthread_join(thread1, &retval);
     printf("thread1 return value(retval) is %d\n", (int)retval);
     printf("thread1 return value(tmp) is %d\n", tmp1);
     if (tmp1 != 0) {
         printf("cannot join with thread1\n");
     }
     printf("thread1 end\n"); 
     tmp2 = pthread_join(thread1, &retval);
     printf("thread2 return value(retval) is %d\n", (int)retval);
     printf("thread2 return value(tmp) is %d\n", tmp1);
     if (tmp2 != 0) {
         printf("cannot join with thread2\n");
     }
     printf("thread2 end\n");
 
}
 void print_message_function( void *ptr ) {
     int i = 0;
     for (i; i<5; i++) {
         printf("%s:%d\n", (char *)ptr, i);
    }
}