Pthreads

[yann]

Hi, what is wrong with this code?

#include <pthread.h>
#include <stdio.h>
#define NUM_THREADS     5

void *PrintHello(void *threadid)
{
   long tid;
   tid = (long)threadid;
   printf("Hello World! It's me, thread #%ld!\n", tid);
   pthread_exit(NULL);
}

int main (int argc, char *argv[])
{
   pthread_t threads[NUM_THREADS];
   int rc;
   long t;
   for(t=0; t<NUM_THREADS; t++){
      printf("In main: creating thread %ld\n", t);
      rc = pthread_create(&threads[t], NULL, PrintHello, (void *)t);
      if (rc){
         printf("ERROR; return code from pthread_create() is %d\n", rc);
         exit(-1);
      }
   }
   pthread_exit(NULL);
}

Its output should look like this:
In main: creating thread 0
In main: creating thread 1
Hello World! It's me, thread #0!
In main: creating thread 2
Hello World! It's me, thread #1!
Hello World! It's me, thread #2!
In main: creating thread 3
In main: creating thread 4
Hello World! It's me, thread #3!
Hello World! It's me, thread #4!

I copied this from the tutorial on POSIX threads.

[quzah]

What is it you think it's supposed to do, that's different from what actually happens?


Quzah.

[yann]

What is it you think it's supposed to do, that's different from what actually happens?


Quzah.

There is an error, when i compile it like this:
gcc d.c -pthread d

d.c: In function ‘main’:
d.c:23: warning: incompatible implicit declaration of built-in function ‘exit’

And like this:
gcc d.c -o d

d.c: In function ‘main’:
d.c:23: warning: incompatible implicit declaration of built-in function ‘exit’
/tmp/ccCnNvZ9.o: In function `main':
d.c.text+0x82): undefined reference to `pthread_create'
collect2: ld returned 1 exit status

[tabstop]

exit is in <stdilb.h>, so you need to include that. And I would have thought that it was -lpthread, not -pthread?

[yann]

exit is in <stdilb.h>, so you need to include that. And I would have thought that it was -lpthread, not -pthread?

But it is still saying there is no such file or directory...

[Dino]

<stdlib.h>, not <stdilb.h>

[yann]

<stdlib.h>, not <stdilb.h>

yes...i know -.-

[tabstop]

<stdlib.h>, not <stdilb.h>

Oops, sorry. There's probably a reason I should put code things in Courier.

[yann]

Oops, sorry. There's probably a reason I should put code things in Courier.

what do you mean?

[tabstop]

what do you mean?

Probably because even after Dino pointed it out it took a long time to tell the difference between <stdlib.h> and <stdilb.h>.

[yann]

now, we were talking about pthread error...

[quzah]

Repost your code with the correct changes, and any errors or warnings you are getting, and try again. The thread is way too off topic / confused to know what it is you really want from us. Also, you typically want to include standard header files before non-standard ones.


Quzah.