W3cubDocs

/C++

std::hash <std::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.

Template parameters

Types - the types of the alternatives supported by the variant object
Type requirements
-The specializations std::hash<T_i> must satisfy Hash for all T_i in Types....

Notes

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.

Example

See also

(C++11)
hash function object
(class template)

© cppreference.com
Licensed under the Creative Commons Attribution-ShareAlike Unported License v3.0.
http://en.cppreference.com/w/cpp/utility/variant/hash