std::mem_fun
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template< class Res, class T > std::mem_fun_t<Res,T> mem_fun( Res (T::*f)() ); |
(1) | ( C++11) ( C++17) |
template< class Res, class T > std::const_mem_fun_t<Res,T> mem_fun( Res (T::*f)() const ); |
(1) | ( C++11) ( C++17) |
template< class Res, class T, class Arg > std::mem_fun1_t<Res,T,Arg> mem_fun( Res (T::*f)(Arg) ); |
(2) | ( C++11) ( C++17) |
template< class Res, class T, class Arg > std::const_mem_fun1_t<Res,T,Arg> mem_fun( Res (T::*f)(Arg) const ); |
(2) | ( C++11) ( C++17) |
- -, . - T operator().
1)
std::mem_fun_t<Res,T>(f) std::const_mem_fun_t<Res,T>(f).2)
std::mem_fun1_t<Res,T,Arg>(f) std::const_mem_fun1_t<Res,T,Arg>(f).C++11 C++17 std::mem_fn std::bind, -.
| f | - |
, f.
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std::mem_fun std::mem_fun_ref , , , — .
std::mem_fun std::mem_fn. , C++11/14: g++/clang++ -std=c++11, cl /std:c++11, .. , , gcc-12, "deprecated declaration", C++98.
#include <functional>
#include <iostream>
struct S
{
int get_data() const { return data; }
void no_args() const { std::cout << "void S::no_args() const\n"; }
void one_arg(int) { std::cout << "void S::one_arg()\n"; }
void two_args(int, int) { std::cout << "void S::two_args(int, int)\n"; }
#if __cplusplus > 201100
int data{42};
#else
int data;
S() : data(42) {}
#endif
};
int main()
{
S s;
std::const_mem_fun_t<int, S> p = std::mem_fun(&S::get_data);
std::cout << "s.get_data(): " << p(&s) << '\n';
std::const_mem_fun_t<void, S> p0 = std::mem_fun(&S::no_args);
p0(&s);
std::mem_fun1_t<void, S, int> p1 = std::mem_fun(&S::one_arg);
p1(&s, 1);
#if __cplusplus > 201100
// auto p2 = std::mem_fun(&S::two_args); // : mem_fun
// -
// . ,
// std::mem_fn :
auto p2 = std::mem_fn(&S::two_args);
p2(s, 1, 2);
// auto pd = std::mem_fun(&S::data); // :
// .
// std::mem_fn:
auto pd = std::mem_fn(&S::data);
std::cout << "s.data = " << pd(s) << '\n';
#endif
}
:
s.get_data(): 42
void S::no_args() const
void S::one_arg(int)
void S::two_args(int, int)
s.data = 42
(C++11) |
( ) |
( C++11)( C++17) |
-, ( ) |