std::hash
From cppreference.com
< cpp | memory | unique ptr
| template<class T, class Deleter> struct hash<unique_ptr<T, Deleter>>; |
(since C++11) | |
The template specialization of std::hash for std::unique_ptr<T, Deleter> allows users to obtain hashes of objects of type std::unique_ptr<T, Deleter>.
For a given std::unique_ptr<T, Deleter> p, this specialization ensures that std::hash<std::unique_ptr<T, Deleter>>()(p) == std::hash<T*>()(p.get()).
[edit] Example
Run this code
#include <iostream> #include <memory> #include <functional> struct Foo { Foo() { std::cout << "Foo...\n"; } ~Foo() { std::cout << "~Foo...\n\n"; } }; int main() { Foo* foo = new Foo(); std::unique_ptr<Foo> up(foo); std::cout << "hash(up): " << std::hash<std::unique_ptr<Foo>>()(up) << '\n'; std::cout << "hash(foo): " << std::hash<Foo*>()(foo) << '\n'; }
Output:
Foo... hash(up): 3686401041 hash(foo): 3686401041 ~Foo...
[edit] See also
| (C++11) |
hash function object (class template) |
