c++: Difference between member and non member functions

Question

What is the difference between member and non-member functions in C++?

Answer 1

A (non-static) member function has an implicit this argument, a non-member doesn't.

Syntactically, you pass that implicit argument on the left of the . or -> operator like.so() or like->so(), instead of as a function argument so( like ).

Likewise, when declaring a member function, you need to do so in the class of which it is a member:

class Class {
public:
    void a_public_member_function();
};

Non-member functions are instead declared outside any class (C++ calls this "at namespace scope").

(Non-static) member functions can also be virtual, but non-member functions (and static member functions) cannot.