"Delphi" Programlama dilinde "Dikdörtgenin Alanını Hesaplama Örneği" ile ilgili örnek kod aşağıda gösterilmiştir.

program RectangleArea;

type
  Rectangle = class
    public
      length, width, area: double;
      procedure GetData();
      procedure ComputeField();
      procedure FieldDisplay();
  end;

procedure Rectangle.GetData();
begin
  writeln('Dikdortgenin uzunlugunu girin: ');
  readln(length);
  writeln('Dikdortgenin genisligini girin: ');
  readln(width);
end;

procedure Rectangle.ComputeField();
begin
  area := length * width;
end;

procedure Rectangle.FieldDisplay();
begin
  writeln('Dikdortgenin Alani: ', area);
end;

var
  r: Rectangle;

begin
  r := Rectangle.Create();
  r.GetData();
  r.ComputeField();
  r.FieldDisplay();
end.