output of client thread

Hello,

I have searched in group. I didnt get answer for my doubts. So i'm
posting this. It is very basic doubt on thread. I wrote below program
to start understanding the thread.

#include <iostream.h>
#include <fstream.h>
#include <stdlib.h>
#include <pthread.h>
#include <errno.h>

extern int errno;
ofstream out;

void* do_loop(void* data)
{
    int i;
    int me = *((int*)data);
    for (i=0; i<10; i++)
         out << " i " << i << " me " << me << endl;
    pthread_exit(NULL);
    return data;
}
void perror(char *str)
{
  cout << str << " : " << errno << endl;
  exit (1);
}

int main(int argc, char* argv[])
{
    int thr_id;
    pthread_t p_thread;
    int a = 1; /* new thread */
    int b = 2; /* main thread */

    thr_id = pthread_create(&p_thread, NULL, do_loop, (void*)&a);

    if ( thr_id != 0 )
     perror("Thread create failed");

    out.open("log.txt", ios::app);
    out << "I'm from main thread " << thr_id << endl;
    out.close();

     return 0;
}

Q1 : Always i get "Thread create failed". I dont find why?
Q2 : I wrote this program to see output writen by client thread in log
file? Is the logic correct?

I have tried the above sample program in HP-Unix B.11.11 U 9000/800 and
SunOS 5.6, Both are running in multiCPUs.... But It didnt work...

thx in advance for your help.

Regards,
Balaji.