okay, um, can anyone tell me how one can exchange the values of two variables without using a temporary variable? 
not tricky after all…
[CODE]Program 1uzd;
Var a,b:integer;
Begin
a:=1;
b:=2;
a:=a+b;
b:=a-b;
a:=b-a;
end.
[/CODE]
apologees :doh:
Why would you want to do that? The C++ STL has swap() which is optimised for your architecture. I guess this one of those “Do it without the obvious way” things.