| Name | Description |
|---|---|
| (since C++17)
| a wrapper that may or may not hold an object (class template) |
| (C++17)
| exception indicating checked access to an optional that doesn't contain a value (class) |
| (C++17)
| specializes the std::hash algorithm (class template specialization) |
| (C++17)
| indicator of optional type with uninitialized state (class) |
Comparison |
|
compares optional objects (function template) |
|
Specialized algorithms |
|
| (C++17)
| specializes the std::swap algorithm (function) |
| (C++17)
| creates an optional object (function template) |
namespace std {
template <class T> class optional;
// In-place construction
struct in_place_t{};
constexpr in_place_t in_place{};
// No-value state indicator
struct nullopt_t{see below};
constexpr nullopt_t nullopt(unspecified);
// Class bad_optional_access
class bad_optional_access;
// Relational operators
template <class T>
constexpr bool operator==(const optional<T>&, const optional<T>&);
template <class T>
constexpr bool operator!=(const optional<T>&, const optional<T>&);
template <class T>
constexpr bool operator<(const optional<T>&, const optional<T>&);
template <class T>
constexpr bool operator>(const optional<T>&, const optional<T>&);
template <class T>
constexpr bool operator<=(const optional<T>&, const optional<T>&);
template <class T>
constexpr bool operator>=(const optional<T>&, const optional<T>&);
// Comparison with nullopt
template <class T> constexpr bool operator==(const optional<T>&, nullopt_t) noexcept;
template <class T> constexpr bool operator==(nullopt_t, const optional<T>&) noexcept;
template <class T> constexpr bool operator!=(const optional<T>&, nullopt_t) noexcept;
template <class T> constexpr bool operator!=(nullopt_t, const optional<T>&) noexcept;
template <class T> constexpr bool operator<(const optional<T>&, nullopt_t) noexcept;
template <class T> constexpr bool operator<(nullopt_t, const optional<T>&) noexcept;
template <class T> constexpr bool operator<=(const optional<T>&, nullopt_t) noexcept;
template <class T> constexpr bool operator<=(nullopt_t, const optional<T>&) noexcept;
template <class T> constexpr bool operator>(const optional<T>&, nullopt_t) noexcept;
template <class T> constexpr bool operator>(nullopt_t, const optional<T>&) noexcept;
template <class T> constexpr bool operator>=(const optional<T>&, nullopt_t) noexcept;
template <class T> constexpr bool operator>=(nullopt_t, const optional<T>&) noexcept;
// Comparison with T
template <class T> constexpr bool operator==(const optional<T>&, const T&);
template <class T> constexpr bool operator==(const T&, const optional<T>&);
template <class T> constexpr bool operator!=(const optional<T>&, const T&);
template <class T> constexpr bool operator!=(const T&, const optional<T>&);
template <class T> constexpr bool operator<(const optional<T>&, const T&);
template <class T> constexpr bool operator<(const T&, const optional<T>&);
template <class T> constexpr bool operator<=(const optional<T>&, const T&);
template <class T> constexpr bool operator<=(const T&, const optional<T>&);
template <class T> constexpr bool operator>(const optional<T>&, const T&);
template <class T> constexpr bool operator>(const T&, const optional<T>&);
template <class T> constexpr bool operator>=(const optional<T>&, const T&);
template <class T> constexpr bool operator>=(const T&, const optional<T>&);
//Specialized algorithms
template <class T> void swap(optional<T>&, optional<T>&) noexcept(see below);
template <class T> constexpr optional<see below> make_optional(T&&);
// Hash support
template <class T> struct hash;
template <class T> struct hash<experimental::optional<T>>;
} // namespace std
© cppreference.com
Licensed under the Creative Commons Attribution-ShareAlike Unported License v3.0.
http://en.cppreference.com/w/cpp/header/optional