Compile and Execute Pascal Online

Program HelloWorld(output);
{$MODE Delphi}

uses
  SysUtils;

////////////////////////////////////////////////////////////////////////////////
function IntToLetters(Number: Cardinal): string;
var
  Modulo: Cardinal;
begin
  Result := '';
  while (Number > 0) do begin
    Modulo := (Number - 1) mod 26;
    Result := Char(65 + Modulo) + Result;
    Number := (Number - Modulo) div 26;
  end;
end {IntToLetters};

////////////////////////////////////////////////////////////////////////////////
function LettersToInt(Letters: string): Cardinal;
var
  i: Integer;
begin
  Letters := UpperCase(Letters);

  Result := 0;
  for i := 1 to Length(Letters) do begin
    Result := Result * 26;
    Inc(Result, Ord(Letters[i]) - 64);
  end;
end {LettersToInt};

procedure TestValue(const i: Integer);
var
  IL: string;
  ILI: Integer;
begin
  Write(i, #9);
  IL := IntToLetters(i);
  Write(IL, #9);
  ILI := LettersToInt(IntToLetters(i)); 
  WriteLn(ILI);
  Assert(i = ILI);
end;


var
  i: Integer;
begin
  for i := 0 to 1024 do begin
    TestValue(i);
  end;
  TestValue(16383);
  TestValue(16384);
  TestValue(16385);
  TestValue(65535);
  TestValue(65536);
  TestValue(65537);
end.