Does this cause memory leak?

Question

Base is the base class and Derived is the derived class.

Base* p = new Derived;
delete p;

Let's assume that the base destructor is not virtual. Does this cause memory leak, if yes, why? And what would be the solution to fix it?

It could but it will depend on the definition of the classes. You will have to show those. — DrC, Apr 03 '15 at 16:29
Let's assume that both the base and derived class have distinct dynamically allocated variables. — Southee, Apr 03 '15 at 16:39
What do you think, @Southee? Will de-referencing a child cause the member data initialized in the parent to be deallocated? *well*? — Don Larynx, Apr 03 '15 at 16:42
@Southee Is this a homework or interview question, or do you have a practical problem to solve? — πάντα ῥεῖ, Apr 03 '15 at 16:43

score 2 · Answer 1 · answered Apr 03 '15 at 16:36

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It might.

It might not.

It might explode your computer.

It has undefined behaviour.

Stop asking about it and simply don't do it. :)

answered Apr 03 '15 at 16:36

Lightness Races in Orbit

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I remember you being a gentleman in answering my question once. So, I'll respect your word on this one. – Southee Apr 03 '15 at 16:37
Anyways, how do I fix it? Like by having the destructor virtual in the base class? – Southee Apr 03 '15 at 16:38
@Southee: Yes, like that. – Lightness Races in Orbit Apr 03 '15 at 16:38

score 0 · Answer 2 · answered Apr 03 '15 at 16:37

"Let's assume that the base destructor is not virtual. Does this cause memory leak, "

Easily, yes. If Derived holds some dynamically allocated memory that should be deleted with it's destructor.

"if yes, why?"

See explanation above. Derived's destructor won't be called.

"And what would be the solution to fix it?"

Make the Base class destructor virtual.

score 0 · Answer 3 · answered Apr 03 '15 at 16:38

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Let suppose that both classes has trivial destructor but Derived class has member with non trivial destructor that Base has not. (std::vector for example) that would leak memory, because destructor of vector will not be called.

answered Apr 03 '15 at 16:38

Luka Rahne

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score 0 · Answer 4 · answered Apr 03 '15 at 16:40

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If there's no dynamic member data in the Base class, it won't cause a memory leak. Still reeks of smell. A code smell.

answered Apr 03 '15 at 16:40

Don Larynx

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Does this cause memory leak?

4 Answers4