need fast reply from pascal programmer plz

Hi guys, I got a problem again. I have to go back to the old program I was creating. I need to add an accept phone number code in there which i have at the end

Code:

---

  BEGIN
        writeln('Enter Customer Phone Number:');              {Ask to enter Phone number}
        readln(phonenumber);
     
end;

---

However, I want to add a loop in there so that it will go back if a letter is entered as a phone number.

Can anyone help?

Its been a while since i used pascal but you dont seemed to have declared the phonenumber variable.

its also a bad idea to have it as an interger since people like to add in dashes and spaces into phone numbers. store it as a string.

sorry no idea if there is a function to look at an int and see if it contains letters.

i need it so that there can't be any letters. but havn't succeeded :(

have you tried declaring phonenumber as an int and sees what happens with letters ?
does it crash?
has your teacher given you a function to use in previous examples to examine an int for chars ?
just looking through some of my old work now to see if i have done something similar.

edit: i would imagine the psudeo code is something like

Code:

---


while phonenumber contains chars do
 
begin
        print "input phone number"
        input "phone number"
end

---

that should loop around until the phonenumber contains no chars but i dont have a clue what the function is you need to use.

This is in Delphi (Object Pascal) but you should get the idea. Bascially, declare the phone number as an integer, then trap the exception that would occur if they enter a character.

If you want to go back up so they have to enter it again, just use a label.

Code:

---

program Project2;

{$APPTYPE CONSOLE}

uses
  SysUtils;

var
 phonenumber :integer;

begin
  writeln('Enter Customer Phone Number:');
  try
    readln(phonenumber);
  except
    writeln('Oops, you enter something other than 0-9');
  end;
  writeln('done');
  readln;

end.

---