program Calculate_Areas;

(*  This program is dedicated to Marsha, a student, who
    was of tremendous help during the debugging stage of
    the text and programs. Thanks Marsha!
*)

var In_Char : char;

procedure Area_Of_Square;
var Length,Area : real;
begin
   Write('Square   Enter length of side ');
   Readln(Length);
   Area := Length * Length;
   Writeln('The area is ',Area:12:4);
end;

procedure Area_Of_Rectangle;
var Width,Height,Area : real;
begin
   Write('Rectangle   Enter width ');
   Readln(Width);
   Write('Enter height ');
   Read(Height);
   Area := Width * Height;
   Writeln('    The area is ',Area:12:4);
end;

procedure Area_Of_Triangle;
var Base,Height,Area : real;
begin
   Write('Triangle     Enter base ');
   Readln(Base);
   Write('Enter height ');
   Read(Height);
   Area := 0.5 * Base * Height;
   Writeln('    The area is ',Area:12:3);
end;

procedure Area_Of_Circle;
var Radius,Area : real;
begin
   Write('Circle    Enter radius ');
   Readln(Radius);
   Area := 3.141592 * Radius * Radius;
   Writeln('The area is ',Area:12:3);
end;

begin  (* main program *)
   repeat
      Writeln;
      Writeln('Please input the first letter of the selection');
      Writeln('Select shape; Square Rectangle Triangle Circle Quit');
      Write('Requested shape is ');
      Repeat until Keypressed;
      Read(Kbd,In_Char);
      case In_Char of
       'S' : Area_Of_Square;
       's' : Area_Of_Square;
       'R' : Area_Of_Rectangle;
       'r' : Area_Of_Rectangle;
       'T' : Area_Of_Triangle;
       't' : Area_Of_Triangle;
       'C' : Area_Of_Circle;
       'c' : Area_Of_Circle;
       'Q' : Writeln('Quit');
       'q' : Writeln('Quit');
       else Writeln(' undefined entry');
      end;
   until (In_Char = 'Q') or (In_Char = 'q');
end.  (* of main program *)