program Encapsulation_1;

type

   Box = object

      length : integer;

      width  : integer;

      constructor Init(len, wid : integer);

      procedure Set_Data(len, wid : integer);

      function Get_Area : integer;

   end;
   constructor Box.Init(len, wid : integer);

   begin

      length := len;

      width := wid;

   end;
   procedure Box.Set_Data(len, wid : integer);

   begin

      length := len;

      width := wid;

   end;
   function Box.Get_Area : integer;

   begin

      Get_Area := length * width;

   end;
var Small, Medium, Large : Box;
begin
   Small.Init(8,8);

   Medium.Init(10,12);

   Large.Init(15,20);
   WriteLn('The area of the small box is ',Small.Get_Area);

   WriteLn('The area of the medium box is ',Medium.Get_Area);

   WriteLn('The area of the large box is ',Large.Get_Area);
end.


Result of execution

The area of the small box is 64

The area of the medium box is 120

The area of the large box is 300