Re: output of client thread

"Jonathan Mcdougall" <>
24 May 2006 09:22:35 -0700
<> wrote:


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.

I don't know what book you are reading, but I think you should have a
look at for other suggestions.

#include <iostream.h>
#include <fstream.h>

These are not standard. They should be

# include <iostream>
# include <fstream>

Standard names are in namespace std. To quickly make your program work,

using namespace std;

but do read about namespaces (especially

#include <stdlib.h>
#include <errno.h>

These should be

# include <cstdlib>
# include <cerrno>

#include <pthread.h>

This does not exist in standard C++, the topic of this newsgroup. For
thread related questions, you'll be better served elsewhere. See for
newsgroup suggestions.

extern int errno;
ofstream out;

Advice: globals are best avoided, *especially* with threads.

void* do_loop(void* data)
    int i;
    int me = *((int*)data);

Use C++ style casts:

int me = *reinterpret_cast<int*>(data);

    for (i=0; i<10; i++)
         out << " i " << i << " me " << me << endl;
    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 */

C++ is not C. See

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

    if ( thr_id != 0 )
     perror("Thread create failed");"log.txt", ios::app);
    out << "I'm from main thread " << thr_id << endl;

     return 0;


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