Category : Pascal Source Code
Archive   : PASTUT.ZIP
Filename : VARREC.PAS

(* Chapter 9 - Program 3 *)
program Variant_Record_Example;

type Kind_Of_Vehicle = (Car,Truck,Bicycle,Boat);

Vehicle = record
Owner_Name : string[25];
Gross_Weight : integer;
Value : real;
case What_Kind : Kind_Of_Vehicle of
Car : (Wheels : integer;
Engine : string[8]);
Truck : (Motor : string[8];
Tires : integer;
Payload : integer);
Bicycle : (Tyres : integer);
Boat : (Prop_Blades : byte;
Sail : boolean;
Power : string[8]);
end; (* of record *)

var Sunfish,Ford,Schwinn,Mac : Vehicle;

begin (* main program *)
Ford.Owner_Name := 'Walter'; (* fields defined in order *)
Ford.Gross_Weight := 5750;
Ford.Value := 2595.00;
Ford.What_Kind := Truck;
Ford.Motor := 'V8';
Ford.Tires := 18;
Ford.Payload := 12000;

with Sunfish do begin
What_Kind := Boat; (* fields defined in random order *)
Sail := TRUE;
Prop_Blades := 3;
Power := 'wind';
Gross_Weight := 375;
Value := 1300.00;
Owner_Name := 'Herman and George';
end;

Ford.Engine := 'flathead'; (* tag-field not defined yet but it *)
Ford.What_Kind := Car; (* must be before it can be used *)
Ford.Wheels := 4;
(* notice that the non variant part is not redefined here *)

Mac := Sunfish; (* entire record copied, including the tag-field *)

if Ford.What_Kind = Car then (* this should print *)
Writeln(Ford.Owner_Name,' owns the car with a ',Ford.Engine,
' engine.');

if Sunfish.What_Kind = Bicycle then (* this should not print *)
Writeln('The sunfish is a bicycle which it shouldn''t be');

if Mac.What_Kind = Boat then (* this should print *)
Writeln('The mac is now a boat with',Mac.Prop_Blades:2,
' propeller blades.');
end. (* of main program *)




{ Result of execution

Walter owns the car with the flathead engine.
The mac is now a boat with three propeller blades.

}