Sample c thread termination exercise

#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
void *t1(void *args) {
 return (void *) 0;
}
void *t2(void *args) {
 printf("thread 2 param[args] = %dn", args);
 pthread_exit((void *) 3);
}
void *t3(void *args) {
 while(1) {
  printf("thread 3 is workingn");
  sleep(1);
 }
}
int main(int argc, char *argv[]) {
 pthread_t thread;
 int err;
 void *status;

 printf("creating thread 1n");
 err = pthread_create(&thread, NULL, t1, NULL);
 if(err) {
  printf("Can not created thread 1n");
  exit(-1);
 }
 pthread_join(thread, &status);
 printf("thread 1 exit return code %dnn", status);
 
 printf("creating thread 2n");
 err = pthread_create(&thread, NULL, t2, (void *) 9);
 if(err) {
  printf("Can not created thread 2n");
  exit(-2);
 }
 pthread_join(thread, &status);
 printf("thread 2 exit return code %dnn", status);

  
 printf("creating thread 3n");
 err = pthread_create(&thread, NULL, t3, NULL);
 if(err) {
  printf("Can not created thread 3n");
  exit(-3);
 }
 sleep(10);
 pthread_cancel(thread);
 pthread_join(thread, &status);
 printf("thread 3 exit return code %dn", status);
 return 1;
}