请教线程问题

homegirl

我试过，pthread_join的第二个参数，获得的是0，而我的线程处理函数返回的是－1050

prc

帖代码吧

iceviewer

:wink: ,如果要用pthread_join的第二个参数获得线程函数的返回值，不能使用return，而应该使用pthread_exit。。。

====以上请注意

prc

NAME
       pthread_create - thread creation

SYNOPSIS
       #include <pthread.h>

       int pthread_create(pthread_t *restrict thread,
              const pthread_attr_t *restrict attr,
              void *(*start_routine)(void*), void *restrict arg);

DESCRIPTION
       The  pthread_create()  function  shall  create a new thread, with attributes specified by attr,
       within a process. If attr is NULL, the default attributes shall  be  used.  If  the  attributes
       specified  by attr are modified later, the thread's attributes shall not be affected. Upon suc-
       cessful completion, pthread_create() shall store the ID of the created thread in  the  location
       referenced by thread.

       The  thread is created executing start_routine with arg as its sole argument. If the start_rou-
       tine returns, the effect shall be as if there was an implicit call to pthread_exit() using  the
       return  value  of  start_routine  as  the exit status. Note that the thread in which main() was
       originally invoked differs from this. When it returns from main(), the effect shall  be  as  if
       there was an implicit call to exit() using the return value of main() as the exit status.

prc

1. 
   
2. #include <pthread.h>
   
3. #include <stdio.h>
   
4. #define NUM_THREADS 1
   
5. 
   
6. void *thread(void *threadid)
   
7. {
   
8.     int ret = rand();
   
9.     printf("thread return %d!\n", ret);
   
10.     return ((void *)ret);
    
11. }
    
12. 
    
13. int main (int argc, char *argv[])
    
14. {
    
15.    pthread_t threads[NUM_THREADS];
    
16.    int rc, t;
    
17.    srand(time(NULL));
    
18.    for(t=0; t<NUM_THREADS; t++){
    
19.       printf("In main: creating thread %d\n", t);
    
20.       rc = pthread_create(&threads[t], NULL, thread, (void *)t);
    
21.       if (rc){
    
22.          printf("ERROR; return code from pthread_create() is %d\n", rc);
    
23.          exit(-1);
    
24.       }
    
25.    }
    
26.     pthread_join(threads[0], &rc);
    
27.     printf("rc=%d\n", rc);
    
28.    pthread_exit(NULL);
    
29. }
    

复制代码

改成return也可以获得thread的返回值。


我的系统是：  cat /proc/versions
Linux version 2.6.16.1 (prc@sw-alg-server) (gcc version 4.1.1 20060525 (Red Hat 4.1.1-1)) #1 SMP Thu Mar 22 09:22:29 CST 2007

在其它系统上的运行结果不知