Character Check
Characters must conform to one or more rules. The program SurnameCheck rejects input strings containing characters other than letters of our alphabet, the hyphen and the apostrophe. This program checks whether each input character is in a set of allowed characters.
program SurnameCheck; {$APPTYPE CONSOLE} uses SysUtils; var strSurname : string; function ValidateSurname (LastName : string) : Boolean; var Error: Boolean; Count : integer; begin Error := False; for Count := 1 to length(LastName) do begin if not (LastName[Count] in ['A'..'Z', 'a'..'z', '-', chr(39)]) then Error := True; end; result := not Error; end; begin repeat write('Please enter your surname. '); readln(strSurname); until ValidateSurname(strSurname); writeln('The surname ', strSurname,' has been validated.'); readln; end.