Why if I delete the pointer to the base class I have a memory leak?

Question

I have the base class and the class that inherits the base class:

class base
{
};

class derived : public base
{ 
    std::string str;
};

I need to manage a derived class using the pointer to the base class, but the following code causes a memory leak:

base* ptr = new derived();
delete ptr;

Have I to cast ptr, or there are better alternatives?

Virtual destructor, Dude! ;) Great link: http://blogs.msdn.com/b/oldnewthing/archive/2004/05/07/127826.aspx — paulsm4, Jul 04 '12 at 19:17
possible duplicate of [Will using delete with a base class pointer cause a memory leak?](http://stackoverflow.com/questions/2100644/will-using-delete-with-a-base-class-pointer-cause-a-memory-leak) — CB Bailey, Jul 04 '12 at 19:18
It actually causes undefined behavior, from the language point of view. — GManNickG, Jul 04 '12 at 19:36

score 7 · Accepted Answer · edited May 23 '17 at 11:48

7

You need a virtual destructor in the base class so the destructor of the derived class is found and called at runtime. See this question and answer for more detail.

edited May 23 '17 at 11:48

Community

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answered Jul 04 '12 at 19:14

tmpearce

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Why if I delete the pointer to the base class I have a memory leak?

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