I'm new to Pascal and FastReport. This question can probably be answered without knowledge of FastReport. Pascal is Delphi. FastReport4.

I have a text box accepting an 8 character string as input. Each character should be numeric. I'm attempting to validate each character as numeric. I've tried using the val function...

Procedure Val(S : String; var R: Real; Code : Integer);
  begin
  end;

procedure thisinputOnChange(Sender: TfrxComponent);
    var
      S     : String;
      error : Integer;
      R     : Real;    
   begin

    S := thisinput.lines.text; 
   Val (S, R, error);        
     If error > 0 then
   Button2.enabled := False;       
  end;

I got this code online. The explanation says that the function will return an error with a code greater than zero if the character cannot be converted to an integer. Is that explanation correct? Am I misinterpreting?

Right now I am trying to set a button's enabled property to false if the validation fails. I might change that to a message. For now, I would like to get it to work by setting the button property.

I'm not sure if I should be using the onChange event or another event. I'm also not sure if I need to send the input to the val function in a loop. Like I said, I'm just learning how to use this function.

I am able to validate the length. This code works...

  procedure thisinputOnChange(Sender: TfrxComponent);

  begin

     if length(thisinput.lines.text) = 8 then          
        Button2.enabled := True;

  end;  

Any suggestions? Should I use the val function or something else? Let me know if I need to provide more info. I might not be able to check back until later, though. Thanks for any help.