// BookQuantity Check
 public bool bookQuantityCheck(string bookQuantity)
 {
     if (string.IsNullOrWhiteSpace(bookQuantity))
     {
         print.bookQuantityOverMessage();
         return(true);
     }
     if (stringCheck(bookQuantity, 5))
     {
         print.ErrorMessage();
         return(true);
     }
     if (bookQuantity.Length == 0 || bookQuantity.Length >= 3)
     {
         print.ErrorMessage();
         return(true);
     }
     return(false);
 }