text: #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  #include <pthread.h>
  #include <unistd.h>
  
  void *thread_main(void *arg){
      int i;
      int cnt = *((int*)arg);
      char *msg = (char*)malloc(sizeof(char)*50);
      strcpy(msg,"Hello,i am thraed~ \n");
  
      for(i=0;i<cnt;i++){
          sleep(1);
          printf("running thread\n");
      }
      return (void*)msg;
  }
  
  int main(int argc, char *argv[]){
      pthread_t t_id;
      int thread_param = 5;
      void *thr_ret;
  
      if(pthread_create(&t_id, NULL, thread_main, (void *)&thread_param) != 0){
          printf("pthread_create() error\n");
          exit(1);
      }
  
      if(pthread_join(t_id, &thr_ret) != 0){
          printf("pthread_join() error");
          exit(1);
      }
      printf("thread return message : %s\n", (char*)thr_ret);
      free(thr_ret);
      return 0;
  }