What is the simplest way to "cast" a member function pointer to a function pointer in C++?

Question

I want to provide a member function for the "comp" parameter of an STL algorithm like lower_bound( ..., Compare comp ). The comp() function accesses a non-static member field so it must itself be a non-static member but the type of a non-static member function pointer is different from that of an ordinary function pointer.

What is the best way around this problem?

Answer 1

It sounds like you want something like boost::bind, to bind the member function pointer to a instance of that class.

Would you care to elaborate your question a bit as to what you're trying to do? Example code, etc.?

Answer 2

This is the most common use of std::mem_fun and std::mem_fun_ref. They're templates that create functors that invoke the specified member function. TR1 adds an std::tr1::bind that's also useful and more versatile (and if you don't have TR1 available, that's based on Boost::bind). C++0x will include std::bind in the standard library (virtually unchanged from TR1).

Answer 3

#include<tr1/functional>

and use mem_fn()