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Message: [QUOTE="JohnQ, post: 2933372"] Different from an identical class? Conceptually how? Lately, I've been pondering, "when does a struct stop being a struct?". To me, that's when its not the same size as a C struct or not layed out the same. So obviously, when a virtual function gets added, then "a struct stops being a struct". I think I can add non-virtual member functions, non-virtual destructor and operators ad infinitum and the "struct will still be a struct" (right?). Even though some explicit syntax would make things more evident: struct A { int data; }; struct B { int data; B(int val){ data = val; } // OK, not virtual }; class StructWrapper { A a_struct; public: A(int val){ a_struct.data = val; } operator A&(){ return a_struct; } }; Where struct B can be used identically to struct A or StructWrapper (I hope!) as the layouts and sizes are the same (assume the operator is being used for StructWrapper when I say "can be used identically"). sizeof(A)==sizeof(B)==sizeof(StructWrapper) But a_struct in StructWrapper would have to be made public to guarantee the same layout as A and B? The equivalent of doing a memcpy of the class or struct (whether I used the right terminology or not I don't know... "bytewise" seems more appropriate). OK, so from what I gather, the compiler may or may not generate the functions/operators depending on the data members. Is it that if there is any non-POD data member, then the functions/operators get generated? Is it always the full set (?): default constructor, copy constructor, assignment operator, (destructor?). John [/QUOTE]

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