std::hash <std::variant>

< cpp‎ | utility‎ | variant
Defined in header <variant>
template <class... Types>
struct hash<std::variant<Types...>>;
(since C++17)

The template specialization of std::hash for the std::variant template allows users to obtain hashes of variant objects.

The specialization std::hash<std::variant<Types...>> is enabled (see std::hash) if every specialization in std::hash<std::remove_const_t<Types>>... is enabled, and is disabled otherwise.

The member functions of this specialization are not guaranteed to be noexcept.

Template parameters

Types - the types of the alternatives supported by the variant object


Unlike std::hash<std::optional>, hash of a variant does not typically equal the hash of the contained value; this makes it possible to distinguish std::variant<int, int> holding the same value as different alternatives.


See also

hash function object
(class template)