Checking boost shared pointer for null

Both p1 and p2 are null, but they are empty too because they don't have any control block associated with them. On the other hand, p3 is null but not empty because it has a control block with a managed nullptr and a reference count of 1.

Simply speaking, a control block keeps a pointer to the managed object and a reference counter, among other bookkeeping data. That is achieved through the aliasing constructor.

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You can just test the pointer as a boolean: it will evaluate to true if it is non-null and false if it is null: if! MSalters MSalters k 8 8 gold badges silver badges bronze badges.

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