Programme d'une calculatrice en pascal

uses
  WinCrt;

var  a,b,r:real;
     x:char;

function add(var a,b: real):real;
begin
r:=a+b;
end;

function sub(var a,b: real):real;
begin
r:=a-b;
end;


function mul(var a,b: real):real;
begin
r:=a*b;
end;

function divis(var a,b: real):real;
begin
r:=a/b;
end;

begin
writeln('calculette PASCAL');
readln(a);
readln(x);
readln(b);
case x of
'+': add(a,b);
'-': sub(a,b);
'*': mul(a,b);
'/': divis(a,b);
end;

writeln(r);
end.