Author: Jonas Bilinkevicius

Is there a simple way of checking if all characters in a string are valid? For 
example valid chars are: "ABCabcd123". If the string I want to check contains 
"AA23c" it is valid, if it contains "AAY" it is invalid.

Answer:

This is one way to do it:

1   { ... }
2   const
3     ValidChars = 'ABCabcd123';
4   type
5     EInvalidText = class(Exception);
6   var
7     iCount: Integer;
8   begin
9     for iCount := 1 to Length(Edit1.Text) do
10      if Pos(Edit1.Text[iCount], ValidChars) = 0 then
11        raise EInvalidText.Create('Invalid text entered.');
12  end;