/* cc thisfile.c -lthread -lpthread */
#include <stdio.h>
#include <pthread.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>

#define NUM_THREADS 5

struct param_t {    /* a sample parameter structure */
  int id;
  char * name;
  int result;      /* out parameter */
};

void *work(void *);   /* thread routine */

int v = 0;  /* global variable */

int  main(int argc, char *argv[]) {

  int i;
  int len;
  pthread_t tid[NUM_THREADS];      /* array of thread IDs */
  struct param_t param[NUM_THREADS];  /* array of parameters */

  /* first build the parameters */
  for (i = 0; i < NUM_THREADS; i ++) {
    param[i].id = i;
    param[i].name = (char*)malloc(32);  /* 32 char name */
    strcpy(param[i].name, "Thread name : ");
    len = strlen(param[i].name);
    param[i].name[len] = (char)(i + '0');
    param[i].name[len+1] = 0;  /* terminate the string */
  }

  for ( i = 0; i < NUM_THREADS; i++)
    pthread_create(&tid[i], NULL, work, &(param[i]));
  for ( i = 0; i < NUM_THREADS; i++)
    pthread_join(tid[i], NULL);
  printf("main() reporting that all %d threads have terminated\n", i);
  printf("v should be %d, it is %d\n", NUM_THREADS, v);
  
  printf("output parameters in each thread\n");
  for (i = 0; i < NUM_THREADS; i ++) {
    printf("thread %d output %d\n", param[i].id, param[i].result);
  }

  return (0);
}  /* main */

void * work(void *arg)   {

  //  int sleep_time = (int)arg;
  //  printf("thread %ld sleeping %d seconds ...\n", pthread_self(), sleep_time);
  //  sleep(sleep_time);
  //  printf("\nthread %ld awakening\n", pthread_self());
  v ++;
  ((struct param_t *)arg)->result = v;  /* set the return param to be v */ 

  return (NULL);
}