function::operator=
Replaces the stored callable object.
function& operator=(null_ptr_type npc);
function& operator=(const function& right);
template<class Fty>
function& operator=(Fty fn);
template<class Fty>
function& operator=(reference_wrapper<Fty> fnref);
Parameters
npc
A null pointer constant.right
The function object to copy.fn
The callable object to wrap.fnref
The callable object reference to wrap.
Remarks
The operators each replace the callable object held by *this with the callable object passed as the operand.
Example
// std_tr1__functional__function_operator_as.cpp
// compile with: /EHsc
#include <functional>
#include <iostream>
int neg(int val)
{
return (-val);
}
int main()
{
std::function<int (int)> fn0(neg);
std::cout << std::boolalpha << "empty == " << !fn0 << std::endl;
std::cout << "val == " << fn0(3) << std::endl;
std::function<int (int)> fn1;
fn1 = 0;
std::cout << std::boolalpha << "empty == " << !fn1 << std::endl;
fn1 = neg;
std::cout << std::boolalpha << "empty == " << !fn1 << std::endl;
std::cout << "val == " << fn1(3) << std::endl;
fn1 = fn0;
std::cout << std::boolalpha << "empty == " << !fn1 << std::endl;
std::cout << "val == " << fn1(3) << std::endl;
fn1 = std::cref(fn1);
std::cout << std::boolalpha << "empty == " << !fn1 << std::endl;
std::cout << "val == " << fn1(3) << std::endl;
return (0);
}
empty == false val == -3 empty == true empty == false val == -3 empty == false val == -3 empty == false val == -3
Requirements
Header: <functional>
Namespace: std