std::mem_fun
From cppreference.com
                    
                                        
                    < cpp | utility | functional
                    
                                                            
                    | Defined in header  <functional> | ||
| template< class Res, class T >  std::mem_fun_t<Res,T> mem_fun( Res (T::*f)() ); | (1) | (until C++17) (deprecated since C++11) | 
| template< class Res, class T >  std::const_mem_fun_t<Res,T> mem_fun( Res (T::*f)() ); | (1) | (until C++17) (deprecated since C++11) | 
| template< class Res, class T, class Arg >  std::mem_fun1_t<Res,T,Arg> mem_fun( Res (T::*f)(Arg) ); | (2) | (until C++17) (deprecated since C++11) | 
| template< class Res, class T, class Arg >  std::const_mem_fun1_t<Res,T,Arg> mem_fun( S (T::*f)(Arg) ); | (2) | (until C++17) (deprecated since C++11) | 
Creates a member function wrapper object, deducing the target type from the template arguments. The wrapper object expects a pointer to an object of type T as the first parameter to its operator().
1) Effectively calls std::mem_fun_t<S,T>(f) or std::const_mem_fun_t<S,T>(f).
2) Effectively calls std::mem_fun1_t<S,T>(f) or std::const_mem_fun1_t<S,T>(f).
This function and the related types were deprecated in C++11 and removed in C++17 in favor of the more general std::mem_fn and std::bind, both of which create callable adapter-compatible function objects from member functions.
| Contents | 
[edit] Parameters
| f | - | pointer to a member function to create a wrapper for | 
[edit] Return value
A function object wrapping f.
[edit] Exceptions
(none)
[edit] Notes
The difference between std::mem_fun and std::mem_fun_ref is that the former produces an function wrapper that expects a pointer to an object, whereas the latter -- a reference.
[edit] Example
| This section is incomplete Reason: no example | 
[edit] See also
| (until C++17) | creates a wrapper from a pointer to member function, callable with a reference to object (function template) | 


