// thread_simple.c -- multithreaded "hello world"

#include <pthread.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>

#define NTHREADS 4

#define errexit(code,str)                          \
  fprintf(stderr,"%s: %s\n",(str),strerror(code)); \
  exit(1);

// this is the thread code
void *hola(void * arg)
{
  int myid=*(int *) arg;

  printf("Hello, world, I'm %d\n",myid);
  return arg;
}

// this is the main thread's code
int main(int argc,char *argv[])
{
  int worker;
  pthread_t threads[NTHREADS];                // holds thread info
  int ids[NTHREADS];                          // holds thread args
  int errcode;                                // holds pthread error code
  int *status;                                // holds return code

  // create the threads
  for (worker=0; worker<NTHREADS; worker++)
  {
    ids[worker]=worker;
    if (errcode=pthread_create(&threads[worker], // thread struct
			       NULL,             // default thread attribute
			       hola,             // start routine
			       &ids[worker]))    // arg to routine
    {
      errexit(errcode,"pthread_create");
    }
  }
  // reap the threads as they exit
  for (worker=0; worker<NTHREADS; worker++)
  {
    // wait for thread to terminate
    if (errcode=pthread_join(threads[worker],(void *) &status))
    { 
      errexit(errcode,"pthread_join");
    }
    // check thread's exit status and release its resources
    if (*status != worker)
    {
      fprintf(stderr,"thread %d terminated abnormally\n",worker);
      exit(1);
    }
  }
  return(0);
}  // end thread_simple.c