c密码不回显

char ch ;
  int index = 0 ;
  char password[31] ;
  while((ch = getch()) != '\r'){
    if(ch != '\b'){
      printf("*") ;
      password[index++] = ch ;
    }
    else{
      printf("\b \b") ;
      index-- ;
    }
  }
  password[index] = '\0' ;
  printf("\n%s",password);