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()).
#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...
| (C++11)
| hash function object (class template) |
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