C++ Passing pointer to non-static member function

Question

Hi everyone :) I have a problem with function pointers
My \'callback\' function arguments are:
1) a function like this: int(*fx)(int,int)
2) an int variable: int a<

Answer 1

Functions cannot be referenced this way:

int (*function3)(int, int) = obj.*function2;

You have to pass the address of the function like this:

int (*function3)(int, int) = std::mem_fn(&A::sub, obj);
//                           ^^^^^^^^^^^^^^^^^^^^^^^^^

The expression function2 decays into a pointer-to-function which allows it to work.