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std::experi...onal::value(3) C++ Standard Libary std::experi...onal::value(3) NAME std::experimental::optional::value - std::experimental::optional::value Synopsis constexpr T& value() &; (1) (library fundamentals TS) constexpr const T & value() const &; constexpr T&& value() &&; (2) (library fundamentals TS) constexpr const T&& value() const &&; Returns the contained value. 1) Equivalent to return bool(*this) ? *val : throw bad_optional_ac- cess();. 2) Equivalent to return bool(*this) ? std::move(*val) : throw bad_optional_access();. Parameters (none) Return value A reference to the contained value. Exceptions std::experimental::bad_optional_access if *this does not contain a value. Notes The dereference operator operator*() does not check if this optional contains a value, which may be more efficient than value(). Example // Run this code #include <experimental/optional> #include <iostream> int main() { std::experimental::optional<int> opt = {}; try { int n = opt.value(); } catch (const std::logic_error& e) { std::cout << e.what() << '\n'; } } Possible output: optional<T>::value: not engaged See also returns the contained value if available, another value value_or otherwise (public member function) operator-> accesses the contained value operator* (public member function) bad_optional_access exception indicating checked access to an optional that (library fundamentals TS) doesn't contain a value (class) Category: * Noindexed pages http://cppreference.com 2024.06.10 std::experi...onal::value(3)
NAME | Synopsis | Parameters | Return value | Exceptions | Notes | Example | Possible output: | See also | Category:
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