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

# define NTHREADS 10

void *thread_function ( void * );

pthread_mutex_t mutex1 = PTHREAD_MUTEX_INITIALIZER;
int counter = 0;

int main ( void )
{
  pthread_t thread_id[NTHREADS];
  int i, j;

  for ( i = 0; i < NTHREADS; i++ )
  {
    pthread_create( &thread_id[i], NULL, thread_function, NULL );
  }

  for(j=0; j < NTHREADS; j++)
  {
    pthread_join( thread_id[j], NULL); 
  }
  
/* 
  Now that all threads are complete I can print the final result.
  Without the join I could be printing a value before all the threads
  have been completed.
*/
  printf("Final counter value: %d\n", counter);

  return 0;
}

void *thread_function(void *dummyPtr)
{
  printf("Thread number %ld\n", pthread_self());
  pthread_mutex_lock( &mutex1 );
  counter++;
  pthread_mutex_unlock( &mutex1 );

  return 0;
}