Questions / Quant development, C++ ownership & memory
Express exclusive ownership
A C++ object has one owning component and must be destroyed automatically when ownership ends. Which standard smart pointer expresses that most directly?
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Answer: C. Use std::unique_ptr for exclusive ownership.
- The problem specifies one owner and automatic destruction when that ownership ends.
- unique_ptr encodes an exclusive owning handle and releases the managed object when the handle ends or is reset.
- Choose shared_ptr when shared ownership is an actual requirement, rather than merely a possible implementation.
Interview shortcut. One owner, automatic cleanup: unique_ptr.
Takeaway. Express the lifetime contract in the ownership type.
Why the other choices fail
- A raw pointer can do it if the owner deletes it in every exit path. Manual delete is not automatic; an exception or early return can skip it.
- Use std::weak_ptr for observed ownership. weak_ptr is non-owning. It cannot provide the required owning lifetime on its own.
- Use std::shared_ptr for shared ownership. shared_ptr represents a potentially shared lifetime. It can manage destruction, but does not express the requested exclusivity as directly.
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