Delphi FMX Verify if EditText contains Numbers Only? - delphi

Question

I need to use different procedure depending on the Edittext.text
i need to call ProcessA(value: string); with Parameters of last 4 Char of string if Edittext.text's first 4 char are string and next 4 are number.
and Call ProcessB(value:integer) with last four numbers as parameter if all 8 char are numbers ?
For Example: If EditText.Text is ASDF1234 then i'll call ProcessA
and if EdiText.Text is 12345678 then i need to call ProcessB.
Show Error if string is like ASD12345 or ASDFG123 or 1234567A or if Numbers are in decimal.
How can i verify this ?

Answer 1

var
Text: string;
function CharInRange(C, FirstC, LastC: char): boolean; inline;
begin
Result := (C >= FirstC) and (C <= LastC);
end;
function IsDigitsOnly(const S: string;
FirstIdx, LastIdx: integer): boolean;
var
I: integer;
begin
for I := FirstIdx to LastIdx do
begin
if not CharInRange(S[I], '0', '9') then
begin
Result := False;
Exit;
end;
end;
Result := True;
end;
function IsUpcaseLettersOnly(const S: string;
FirstIdx, LastIdx: integer): boolean;
var
I: integer;
C: char;
begin
for I := FirstIdx to LastIdx do
begin
C := S[I];
if not CharInRange(C, 'A', 'Z') then
begin
Result := False;
Exit;
end;
end;
Result := True;
end;
procedure BadInput;
begin
raise Exception.Create('Bad Input');
end;
begin
Text := EditText.Text;
if Length(Text) <> 8 then
begin
BadInput;
end
else if IsUpcaseLettersOnly(Text, 1, 4)
and IsDigitsOnly(Text, 5, 8) then
begin
ProcessA(Copy(Text, 5, 4));
end
else if IsDigitsOnly(Text, 1, 8) then
begin
ProcessB(StrToInt(Copy(Text, 5, 4)));
end
else
begin
BadInput;
end;
end;
Alternatively
uses
..., System.RegularExpressions;
var
Text: string;
begin
Text := EditText.Text;
// I know this can be done better using a
// single regex expression with capture groups,
// but I don't know the correct code to do that...
if TRegEx.IsMatch(Text, '^[A-Z]{4}[0-9]{4}$') then
begin
ProcessA(Copy(Text, 5, 4));
end
else if TRegEx.IsMatch(Text, '^[0-9]{8}$') then
begin
ProcessB(StrToInt(Copy(Text, 5, 4)));
end
else
begin
raise Exception.Create('Bad Input');
end;
end;