Mega Code Archive
IsFloat function
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Title: IsFloat function
Question: How do you tell if a string is a valid float?
Answer:
I was asked the question "How do I know if a string is a float?" Well, I immediately though of StrToFloat. But I hate the idea of raising an exception if it fails and sides I may not want the value just yet. Looking at StrToFloat I realized that I could use TextToFloat instead to tell me if the value is a valid float.
My simple example:
unit Unit1;
interface
uses
Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
StdCtrls;
type
TForm1 = class(TForm)
Button1: TButton;
Edit1: TEdit;
procedure Button1Click(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;
var
Form1: TForm1;
implementation
{$R *.DFM}
function IsFloat(S: string): boolean;
var
f: extended;
begin
Result := TextToFloat(PChar(S), f, fvExtended);
end;
procedure TForm1.Button1Click(Sender: TObject);
begin
if IsFloat(Edit1.text) then
Showmessage('Yes')
else
Showmessage('No');
end;
end.
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