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This article introduces the knowledge of "when should C++ use unique_ptr instead of shared_ptr". In the operation of practical 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!

R.21: unique_ptr instead of shared_ptr should be used when shared ownership is not required

Reason (reason)

Unique_ptr is conceptually simpler, the actions are more predictable (you know when the destructions occur) and faster (no implicit maintenance of usage counts is required).

Example, bad (negative example)

Increase and maintain reference counts unnecessarily.

Void f ()

{

Shared_ptr base = make_shared ()

/ / use base locally, without copying it-- refcount never exceeds 1

} / / destroy base

Example (sample)

The following code is more efficient:

Void f ()

{

Unique_ptr base = make_unique ()

/ / use base locally

} / / destroy baseEnforcement (implementation recommendations)

(simple) issue a warning if a function uses shared_ptr to manage locally allocated objects within it, but never returns the smart pointer or passes it to a function that requires shared_ptr&. Unique_ptr is recommended.

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