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This article introduces the knowledge of "what is the role of the return value of T* in C++". In the operation of actual cases, many people will encounter such a dilemma, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

F.42 T* return value should only be used to indicate the location Reason (reason)

That's what pointers are good for. Returning a T* to transfer ownership is a misuse.

This is the strength of pointers. Using T* to return ownership is the wrong use.

Example (sample)

Node* find (Node* t, const string& s) / / find s ina binary tree of Nodes {if (! t | | t-> name = = s) return t; if ((auto p = find (t-> left, s) return p; if ((auto p = find (t-> right, s)) return p; return nullptr;}

If it isn't the nullptr, the pointer returned by find indicates a Node holding s. Importantly, that does not imply a transfer of ownership of the pointed-to object to the caller.

If the return value is not nullptr, the pointer returned by find represents the Node that holds s. Importantly, it does not contain the meaning of passing ownership of the object pointed to by the pointer to the caller.

Note (Note)

Positions can also be transferred by iterators, indices, and references. A reference is often a superior alternative to a pointer if there is no need to use nullptr or if the object referred to should not change.

Locations can also be passed through iterators, indexes, and references. If you don't need to use nullptr or the object doesn't want to be modified, references are usually a better choice than pointers.

Note (Note)

Do not return a pointer to something that is not in the caller's scope; see F.43.

Do not return a pointer to something that is not within the scope of the caller.

Enforcement (implementation recommendations)

Flag delete, std::free (), etc. Applied to a plain tipped. Only owners should be deleted.

Indicates operations such as delete,std::free () that are applied to the direct pointer. Only the owner can delete.

Flag new, malloc (), etc. Assigned to a plain tipped. Only owners should be responsible for deletion.

Tag processes such as new,malloc (), which assigns the result to a direct pointer. Only the owner is responsible for destruction.

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