Thread: reference with pointers?

Hello,

I am still unfamiliar with some aspects with C++ programming and have a question:

I was looking at some code that is part of a test suite where there was a function:


void *a_thread_func()
{

pthread_exit(0);
return NULL;
}

what exactly does this ( "void *a_thread_func()" ) mean??

It is being used for invoking threads in the following line:

pthread_create(&new_th, &new_attr, a_thread_func, NULL);


I have included/attached the code and the header (only 2 files), but when I compile this code I get an error of :

"Passing 'void * (*) () ' as argument 3 of 'pthread_create(pthread_t *, const pthread_attr_t *, void (*)(void*), void *)'

I was wondering if I need to cast something, although I am not sure what to do??

I thank in advance for any help that can be provided. It is appreciated

Sorry about that, here are the 2 attached files: 1-1.c and posixtest.h.

Thanks for any help!!

HI, thanks for your reply, unfortunately it is still giving me the same error.
I guess the attachments didn't stick, but here they are:

THanks for any help, it is greatly appreciated :


1-1.c: ( and posixtest.h is pasted below

#include <pthread.h>
#include <stdio.h>
#include <errno.h>
#include "posixtest.h"


void *a_thread_func()
{

pthread_exit(0);
return NULL;
}

int main()
{
pthread_t new_th;
pthread_attr_t new_attr;
int ret;

/* Initialize attribute */
if(pthread_attr_init(&new_attr) != 0)
{
perror("Cannot initialize attribute object\n");
return PTS_UNRESOLVED;
}

/* Destroy attribute */
if(pthread_attr_destroy(&new_attr) != 0)
{
perror("Cannot destroy the attribute object\n");
return PTS_UNRESOLVED;
}

/* Creating a thread, passing to it the destroyed attribute, should
* result in an error value of EINVAL (invalid 'attr' value). */
ret=pthread_create(&new_th, &new_attr, a_thread_func, NULL);

if(ret==EINVAL)
{
printf("Test PASSED\n");
return PTS_PASS;
}
else if((ret != 0) && ((ret == EPERM) || (ret == EAGAIN)))
{
perror("Error created a new thread\n");
return PTS_UNRESOLVED;
}
else if(ret==0)
{
printf("Test PASSED: NOTE*: Though returned 0 when creating a thread with a destroyed attribute, this behavior is compliant with garbage-in-garbage-out. \n");
return PTS_PASS;
} else
{
printf("Test FAILED: (1) Incorrect return code from pthread_create(); %d not EINVAL or (2) Error in pthread_create()'s behavior in returning error codes \n", ret);
return PTS_FAIL;
}

}

------------------------------
posixtest.h:


#define PTS_PASS 0
#define PTS_FAIL 1
#define PTS_UNRESOLVED 2
#define PTS_UNSUPPORTED 4
#define PTS_UNTESTED 5