Question about accessor functions

[CoffeeAddict19]

Sort of newbie question here. I've read in places that you should avoid returning large class objects (particulary the class String) or datastructures, and instead should call a function and send it back by reference. Like this (ExpressionData is a structure with 3 cstrings): void CRatiosNewSearchStringDialog::GetExpressionData(SearchExpressionType & Expression) { Expression = ExpressionData; } as opposed to: SearchExpressionType CRatiosNewSearchStringDialog::GetExpressionData() { return ExpressionData; } Where should I draw the line between a large and small piece of data i.e should I bother with all this for a single CString? When should I use return and when should I sent it back by reference? Advice?