std::weak_ptr::use_count

 

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std::weak_ptr

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weak_ptr::use_count

weak_ptr::expired

weak_ptr::lock

weak_ptr::owner_before

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std::swap

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std::atomic<std::weak_ptr> (C++20)

Deduction guides(C++17)

 

long use_count() const noexcept;		(since C++11)

Returns the number of shared_ptr instances that share ownership of the managed object, or ​0​ if the managed object has already been deleted, i.e. *this is empty.

Parameters

(none)

Return value

The number of shared_ptr instances sharing the ownership of the managed object at the instant of the call.

Notes

expired() may be faster than use_count(). This function is inherently racy, if the managed object is shared among threads that might be creating and destroying copies of the shared_ptr: then, the result is reliable only if it matches the number of copies uniquely owned by the calling thread, or zero; any other value may become stale before it can be used.

See also

expired

checks whether the referenced object was already deleted (public member function)