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std::experimental::optional::value(3) | C++ Standard Libary | std::experimental::optional::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_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)
Category:¶
* Noindexed pages
2024.06.10 | http://cppreference.com |