NAME¶

std::reference_wrapper::get,std::reference_wrapper::operatorT& - std::reference_wrapper::get,std::reference_wrapper::operatorT&

Synopsis¶

operator T& () const noexcept; (1) (since C++11)
(constexpr since C++20)
T& get() const noexcept; (2) (since C++11)
(constexpr since C++20)

Returns the stored reference.

Parameters¶

(none)

Return value¶

The stored reference.

Example¶

// Run this code

#include <cassert>
#include <functional>
#include <map>
#include <optional>
#include <string_view>

using Map = std::map<std::string_view, int>;
using Opt = std::optional<std::reference_wrapper<Map::value_type>>;

Opt find(Map& m, std::string_view s)
{
auto it = m.find(s);
return it == m.end() ? Opt{} : Opt{*it};
}

int main()
{
Map m{{"A", 1}, {"B", 2}, {"C", 3}};

if (auto opt = find(m, "C"); opt)
opt->get().second = 42;
// std::optional::operator->() returns reference to std::reference_wrapper, then
// reference_wrapper::get() returns reference to map::value_type, i.e. std::pair

assert(m["C"] == 42);
}

See also¶

operator() calls the stored function
(public member function)