Question

what is the difference between a static and a non static member function ?

Answer 1

This differs from language to language, but in C or C++03 functions generally map on assembly functions; that is they exist once in memory (whether free functions, class functions or class static functions) and take arguments as parameters, including a this pointer for member functions that is implicit.

In C++11, lambda functions introduce a novelty: each instance of the so-called function will carry some state. From an implementation point of view, it therefore means that a "regular" function needs be created and it is associated to an anonymous bundle of data (if necessary). The function need not be duplicated each time the lambda is created, but the data does. One helpful figure is to remember that lambdas (in C++) replace function objects (or predicate objects): they are just syntactic sugar, the implementation is similar.