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// reference_wrapper::operator()
#include <iostream> // std::cout
#include <functional> // std::reference_wrapper, std::plus
struct AB {
int a,b;
int sum() {return a+b;}
};
int ten() {return 10;} // function
int main () {
std::plus<int> plus_ints; // function object
int AB::* p_a = &AB::a; // pointer to data member
int(AB::* p_sum)() = &AB::sum; // pointer to member function
// construct reference_wrappers using std::ref:
auto ref_ten = std::ref(ten); // function
auto ref_plus_ints = std::ref(plus_ints); // function object
auto ref_AB_sum = std::ref(p_sum); // pointer to member function
auto ref_AB_a = std::ref(p_a); // pointer to data member
AB ab {100,200};
// invocations:
std::cout << ref_ten() << '\n';
std::cout << ref_plus_ints(5,10) << '\n';
std::cout << ref_AB_sum(ab) << '\n';
std::cout << ref_AB_a( ab) << '\n';
std::cout << ref_AB_a(&ab) << '\n'; // (also ok with pointer)
return 0;
}
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