std::reference_wrapper::get, std::reference_wrapper::operator T& - cppreference.com (original) (raw)
| 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.
[edit] Parameters
(none)
[edit] Return value
The stored reference.
[edit] Example
#include #include #include #include #include using Map = std::map<std::string_view, int>; using Opt = std::optional<std::reference_wrapperMap::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); }