#include <pthread.h>
#include <stdio.h>
void* hello(void* id) {
   printf("%d: Hello world!\n", *((int*) id));
   return 0;
}
int main(int argc, char* argv[])
{
   const int COUNT = 5;
   int i;
   pthread_t thread[COUNT];
   int ids[COUNT];
   for (i = 0; i <COUNT; i++) {
      ids[i] = i;
      int retval = pthread_create(&thread[i], NULL, hello, &ids[i]);
      if (retval) {
         perror("pthread_create failed");
         return 1;
      }
   }
   for (i = 0; i <COUNT; i++) pthread_join(thread[i], NULL);
      return 0;
}