program Inheritance_1;

{ ******************** class definitions **********************}
type

   Vehicle = object

      Wheels : integer;

      Weight : real;

      constructor Init(In_Wheels : integer; In_Weight : real);

      function Get_Wheels : integer;

      function Get_Weight : real;

      function Wheel_loading : real;

   end;
   Car = object(Vehicle)

      Passenger_Load : integer;

      constructor Init(In_Wheels : integer;

                       In_Weight : real;

                       People    : integer);

      function Passengers : integer;

   end;
   Truck = Object(Vehicle)

      Passenger_Load : integer;

      Payload        : real;

      constructor Init(People : integer;

                       Max_Load : real;

                       In_Wheels : integer;

                       In_Weight : real);

      function Efficiency : real;

      function Wheel_Loading :real;

   end;
{ ********************* class implementations ******************** }
   constructor Vehicle.Init(In_Wheels : integer; In_Weight : real);

   begin

      Wheels := In_Wheels;

      Weight := In_Weight;

   end;
   function Vehicle.Get_Wheels : integer;

   begin

      Get_Wheels := Wheels;

   end;
   function Vehicle.Get_Weight : real;

   begin

      Get_Weight := Weight;

   end;
   function Vehicle.Wheel_loading : real;

   begin

      Wheel_Loading := Weight/Wheels;

   end;
   constructor Car.Init(In_Wheels : integer;

                        In_Weight : real;

                        People    : integer);

   begin

      Wheels := In_Wheels;

      Weight := In_Weight;

      Passenger_Load := People;

   end;
   function Car.Passengers : integer;

   begin

      Passengers := Passenger_Load;

   end;
   constructor Truck.Init(People : integer;

                          Max_Load : real;

                          In_Wheels : integer;

                          In_Weight : real);

   begin

      Passenger_Load := People;

      Payload := Max_Load;

      Vehicle.Init(In_Wheels, In_Weight);

   end;
   function Truck.Efficiency : real;

   begin

      Efficiency := 100.0 * Payload / (Payload + Weight);

   end;
   function Truck.Wheel_Loading : real;

   begin

      Wheel_Loading := (Weight + Payload)/Wheels;

   end;
{ ************************ main program ************************** }
var Unicycle : Vehicle;

    Sedan    : Car;

    Semi     : Truck;
begin
   Unicycle.Init(1, 12.0);

   Sedan.Init(4, 2100.0, 5);

   Semi.Init(1, 25000.0, 18, 5000.0);
   WriteLn('The unicycle weighs ', Unicycle.Get_Weight:5:1,

           ' pounds, and has ', Unicycle.Get_Wheels, ' wheel.');
   WriteLn('The car weighs ', Sedan.Get_Weight:7:1,

           ' pounds, and carries ', Sedan.Passengers,

           ' passengers.');
   WriteLn('The semi has a wheel loading of ', Semi.Wheel_Loading:8:1,

           ' pounds per tire,');

   WriteLn(' and has an efficiency of ', Semi.Efficiency:5:1,

           ' percent.');
   with Semi do

   begin

      WriteLn('The semi has a wheel loading of ', Wheel_Loading:8:1,

              ' pounds per tire,');

      WriteLn(' and has an efficiency of ', Efficiency:5:1,

              ' percent.');

   end;

end.

Result of execution
The unicycle weighs  12.0 pounds, and has 1 wheel.

The car weighs  2100.0 pounds, and carries 5 passengers.

The semi has a wheel loading of   1666.7 pounds per tire,

 and has an efficiency of 83.3 percent.

The semi has a wheel loading of   1666.7 pounds per tire,

 and has an efficiency of 83.3 percent.