std::weak_ptr::use_count

long use_count() const;

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.

Exceptions

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.

Example

See also