2進⇔10進数変換

BinUtils.dpr

program BinUtils;

{$APPTYPE CONSOLE}

{$R *.res}

uses
  System.SysUtils, System.Classes;

function FromBinary(const AValue: String): Integer;
begin
  Result := 0;

  var Shift := 0;
  for var i := AValue.Length - 1 downto 0 do
  begin
    if AValue.Chars[i] = '1' then
      Inc(Result, 1 shl Shift);
    Inc(Shift);
  end;
end;

function ToBinary(AValue: Integer): String;
const
  BIN: array [Boolean] of String = ('0', '1');
begin
  Result := '';

  var SB := TStringBuilder.Create;
  try
    while AValue > 0 do
    begin
      SB.Insert(0, BIN[Odd(AValue)]);
      AValue := AValue shr 1;
    end;

    Result := SB.ToString;
  finally
    SB.Free;
  end;
end;

begin
  const NUM = $100;
  try
    var Bin := ToBinary(NUM);
    Writeln('Num: ', NUM);
    Writeln('Bin: ', Bin);
    Writeln('Dec: ', FromBinary(Bin));
  except
    on E: Exception do
      Writeln(E.ClassName, ': ', E.Message);
  end;

  Readln;
end.