C Shared Ptr Get Reference Count
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Returns the stored pointer.
C shared ptr get reference count. It maintains the reference count of its contained pointer in cooperation with all copies of the shared ptr. Passing smart pointers is an important topic which is seldom addressed. It is a reference counting ownership model i e. Destruction of the original shared ptr will leave a dangling with a use count of 1.
When a weak ptr is created from a shared ptr it refers to the same control block but does not share the ownership of the managed object it is not possible to directly access the. An std weak ptr is a smart pointer that serves as a weak reference to an std shared ptr managed object. This ends with the c core guidelines because they have six rules for passing std shared ptr and std unique ptr. Even if external pointers are freed the internal pointers will still count and the reference count will not reach 0.
In multithreaded environment this does not imply that the destructor of the managed object. I know how i can get the shared ptr use count using. Library implementations are not required to keep a count of any particular set of owners and thus it may not be efficient to call this function. Parameters none return valuthe number of shared ptr instances managing the current object or 0 if there is no managed object.
Or the callee can decide to create a shared ptr based on the reference and become a shared owner. A control block also keeps the count of weak ptr associated with it in a weak counter. That is at least with the most naïve implementation. The stored pointer i e the pointer returned by this function may not be the owned pointer i e the pointer deleted on object destruction if the shared ptr object is an alias i e alias constructed objects and their copies.
Because the implementation uses reference counting cycles of shared ptr instances will not be reclaimed. Pass the shared ptr by reference or const reference. The six rules violate the import dry don t repeat yourself principle for software development at the end we have only four rules what makes our life as a software developer a lot easier. So the counter is incremented each time a new pointer points to the resource and decremented when the destructor of the object is called.
In this case the reference count isn t incremented and the callee can access the pointer as long as the caller doesn t go out of scope. For example if main holds a shared ptr to a which directly or indirectly holds a shared ptr back to a a s use count will be 2. Is it possible to get the weak reference count to a shared ptr. If this is an empty shared ptr the function returns zero.
Returns the number of shared ptr objects that share ownership over the same pointer as this object including it. The stored pointer points to the object the shared ptr object dereferences to which is generally the same as its owned pointer.
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