std::shared_ptr<T>::owner_hash

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Memory management library
(exposition only*)
Uninitialized memory algorithms
(C++17)
(C++17)
(C++17)
(C++20)
Constrained uninitialized
memory algorithms
(C++20)
C Library

Allocators
(C++11)
(C++11)
Memory resources
Garbage collection support
(C++11)(until C++23)
(C++11)(until C++23)
(C++11)(until C++23)
(C++11)(until C++23)
(C++11)(until C++23)
(C++11)(until C++23)
Uninitialized storage
(until C++20*)
(until C++20*)
(until C++20*)
Explicit lifetime management
std::size_t owner_hash( ) const noexcept ;
(since C++26)

Returns an unspecified value such that for any object other where owner_equal(other) is true, owner_hash() == other.owner_hash() is true

This hashing is used to make shared and weak pointers usable as keys in unordered associative containers, typically through std::owner_hash.

Return value

A value that is identical for any std::shared_ptr or std::weak_ptr object sharing the same ownership.

Notes

Feature-test macro Value Std Feature
__cpp_lib_smart_ptr_owner_equality 202306L (C++26) Enabling the use of std::shared_ptr as keys in unordered associative containers

Example

See also

(C++26)
provides owner-based hashing for shared and weak pointers
(class)