quote:Original post by DevLiquidKnight
I was wondering when do you use the "friend" statement or whatever in C++. Also when is it best to use a union?

My friend said unions were faster then a typedef struct because he said they are in the same location in memory, which makes them not use as much memory or something. Im not sure if this is right. Im also not sure when to use it if anyone can give me an idea of when id use it?

I also was wondering when you use a friend data type or object type and what type of things it will allow me to do that I can not do normally?

Friend is a cheating way around some OO rules. Use sparingly - lots of posters seem to have posted good links about this already. Particularly useful for operator overloading.

Union - useful for creating something equivalent to a visual basic variant - and COM uses the mechanism to do something like that. Like friend though, it''s use should be sparingly. Optimisation of this sort should really only be bothered with if a. You are a flash git looking for trouble or b. you are working with very limited memory. Nowadays for PC programmers (and in the gaming domain) unless your union is doing something very very generic (buffer for network comms perhaps?) you are probably a.