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_access();
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)