(* Chapter 13 - Program 2 *)
unit Perims;
(*****************************************************************)
(*                                                               *)
(* This unit contains three procedures to calculate perimieters  *)
(* of three geometric shapes.                                    *)
(*                                                               *)
(*****************************************************************)

interface
   procedure Perimeter_Of_Circle(Radius : real;
                                 var Perimeter : real );
   procedure Perimeter_Of_Square(Length_Of_Side : real;
                                 var Perimeter : real);
   procedure Perimeter_Of_Rectangle(Length,Width : real;
                                    var Perimeter : real);

implementation

var My_Pi : real;


procedure Perimeter_Of_Circle;
begin
   Perimeter := My_Pi * 2.0 * Radius;
end;


procedure Perimeter_Of_Square;
begin
   Perimeter := 4.0 * Length_Of_Side;
end;


procedure Perimeter_Of_Rectangle;
begin
   Perimeter := 2.0 * (Length + Width);
end;


begin                   (* This is the initialization code *)
   My_Pi := 3.14159267;
end.  (* of unit Perimeters *)