Re: Does deleting a container of pointers also delete the (contained) pointers?

From: Cy Edmunds (cedmunds_at_spamless.rochester.rr.com)
Date: 11/04/03 

Date: Tue, 04 Nov 2003 02:29:17 GMT

"Xamalek" <xamalek-nospam-spammm@yahoo.com> wrote in message
news:hgBpb.13325$Vg7.6043@newssvr14.news.prodigy.com...
> Greetings,
>
> I have a question. When using an STL container, does deleting a container
of
> pointers also call delete on the (contained) pointers?

No. Imagine if it did:

void disaster()
{
    std::vector<int*> v;
    int k;
    v.push_back(&k);
} // undefined behavior here if std::vector deleted contained pointers

There is no way for the collection to tell if the pointer was obtained from
the new() operator or not.

>
> For example, if I have (ignore the fluff, it is simply used to explain my
> issue)
>
> struct Proc
> {
> int uid;
> int pid;
> int parent_id;
> };
>
> and then I have
>
> queue<Proc*> Q = new queue<Proc*>;

Huh? I think you mean:

queue<Proc*> *Q = new queue<Proc*>;

although why you would dynamically allocate it is beyond me.

>
> // I then populate the queue with Proc types
>
>
> If I do a
>
> delete Q;
>
> will that destroy the queue and the inner elements as well, or do I have
to
> do the work of ensuring that delete is also called on all the Proc*'s
> (contained by the queue) as well?

You have to delete them yourself unless you use a reference counted smart
pointer.

>
> Sincerely,
> X
>
> 

-- 
Cy
http://home.rochester.rr.com/cyhome/

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