std::mem_fun_ref

From cppreference.com
< cpp‎ | utility‎ | functional
C++
Utilities library
General utilities
Relational operators (deprecated in C++20)
Integer comparison functions
(C++20)(C++20)(C++20)
(C++20)
Swap and type operations
(C++20)
(C++14)
(C++11)
(C++23)
(C++11)
(C++23)
(C++11)
(C++11)
(C++17)
Common vocabulary types
(C++11)
(C++17)
(C++17)
(C++17)
(C++11)
(C++11)
(C++17)
(C++17)
(C++23)



Function objects
Function invocation
(C++17)(C++23)
Identity function object
(C++20)
Transparent operator wrappers
(C++14)
(C++14)
(C++14)
(C++14)  
(C++14)
(C++14)
(C++14)
(C++14)
(C++14)
(C++14)
(C++14)
(C++14)
(C++14)
(C++14)
(C++14)
(C++14)
(C++14)
(C++14)
(C++14)

Old binders and adaptors
(until C++17*)
(until C++17*)
(until C++17*)
(until C++17*)
(until C++17*)  
(until C++17*)
(until C++17*) (until C++17*) (until C++17*) (until C++17*)
(until C++20*)
(until C++20*)
(until C++17*)(until C++17*)
(until C++17*)(until C++17*)

mem_fun_ref
(until C++17*)
(until C++17*) (until C++17*) (until C++17*) (until C++17*)
(until C++20*)
(until C++20*)
Defined in header <functional>
template < class Res, class T >
std::mem_fun_ref_t <Res,T> mem_fun_ref( Res (T:: *f) ( ) ) ;
(1) (deprecated in C++11)
(removed in C++17)
template < class Res, class T >
std::const_mem_fun_ref_t <Res,T> mem_fun_ref( Res (T:: *f) ( ) const ) ;
(1) (deprecated in C++11)
(removed in C++17)
template < class Res, class T, class Arg >
std::mem_fun1_ref_t <Res,T,Arg> mem_fun_ref( Res (T:: *f) (Arg) ) ;
(2) (deprecated in C++11)
(removed in C++17)
template < class Res, class T, class Arg >
std::const_mem_fun1_ref_t <Res,T,Arg> mem_fun_ref( Res (T:: *f) (Arg) const ) ;
(2) (deprecated in C++11)
(removed in C++17)

Creates a member function wrapper object, deducing the target type from the template arguments. The wrapper object expects a reference to an object of type T as the first parameter to its operator()

1) Effectively calls std::mem_fun_ref_t <S,T> (f) or std::const_mem_fun_ref_t <S,T> (f)
2) Effectively calls std::mem_fun1_ref_t <S,T> (f) or std::const_mem_fun1_ref_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

Parameters

f - pointer to a member function to create a wrapper for

Return value

A function object wrapping f.

Exceptions

May throw implementation-defined exceptions.

Notes

The difference between std::mem_fun and std::mem_fun_ref

Example

Uses std::mem_fun_ref to bind std::string's member function size()

Run this code
#include <algorithm>
#include <functional>
#include <iostream>
#include <iterator>
#include <string>
#include <vector>
 
int main()
{
    std::vector<std::string> v = {"once", "upon", "a", "time"};
    std::transform(v.cbegin(), v.cend(),
                   std::ostream_iterator<std::size_t>(std::cout, " "),
                   std::mem_fun_ref(&std::string::size));
}

Output: 

4 4 1 4

See also

(deprecated in C++11)(removed in C++17)
 creates a wrapper from a pointer to member function, callable with a pointer to object
(function template)
Retrieved from "https://en.cppreference.com/mwiki/index.php?title=cpp/utility/functional/mem_fun_ref&oldid=152262