Test if string is numeric

// Test if string is numeric
function IsNumeric(s : string): Boolean;
var
P : PChar;
sText : String;
begin
if Length(s) = 0 then
begin
Result := False;
Exit;
end;

sText := s;

sText := StringReplace(sText, ‘,’, ”, [rfReplaceAll]);

P := PChar(sText);
Result := False;

while (P^ <> #0) do
begin
if not (P^ in [‘0’..’9′]) then Exit;
// if not ((P^ in [‘0’..’9′]) Or (P^ = ‘,’)) then Exit;

Inc(P);
end;

Result := True;
end;