#include <string.h>
#include <stdio.h>
#include <unistd.h>
void prtastr(const char* s, int fd, int n){
  int j , k;
  for(k = 0; k < strlen(s); k++){
    if(write(fd, &s[k], 1) != 1){
      fprintf(stderr, "Write in prtastr failed!\n");
      break;
    }
    for(j = 0; j < n; j++);
  }
}