pthread example - hello program

Another simple pthread example. Threads are created by calling pthread_create() function. pthread_join() just waits for the specified thread to finish. The program terminates when all the threads are finished. The pthread example is shown below.

---

/*
 * p_hello.c -- a hello program (in pthread)
 */
#include <stdio.h>
#include <sys/types.h>
#include <pthread.h>

#define MAX_THREAD 1000

typedef struct {
 int id;
} parm;

void *hello(void *arg)
{
 parm *p=(parm *)arg;
 printf("Hello from node %d\n", p->id);
 return (NULL);
}

void main(int argc, char* argv[]) {
 int n,i;
 pthread_t *threads;
 pthread_attr_t pthread_custom_attr;
 parm *p;

 if (argc != 2)
 {
  printf ("Usage: %s n\n  where n is no. of threads\n",argv[0]);
  exit(1);
 }

 n=atoi(argv[1]);

 if ((n < 1) || (n > MAX_THREAD))
 {
  printf ("The no of thread should between 1 and %d.\n",MAX_THREAD);
  exit(1);
 }

 threads=(pthread_t *)malloc(n*sizeof(*threads));
 pthread_attr_init(&pthread_custom_attr);

 p=(parm *)malloc(sizeof(parm)*n);
 /* Start up thread */

 for (i=0; i<n; i++)
 {
  p[i].id=i;
  pthread_create(&threads[i], &pthread_custom_attr, hello, (void *)(p+i));
 }

 /* Synchronize the completion of each thread. */

 for (i=0; i<n; i++)
 {
  pthread_join(threads[i],NULL);
 }
 free(p);
}