pointer to a vector? shall i delete it or clear it?

[ypjofficial]

Hello All,

In my program I am using a pointer to a vector
vector<XYZ> * vptr = new vector<XYZ>;

and also the XYZ class has a char* as one of its member.I have created
all the copy constructor, assignment operator and destructor (The Big
Three ) for XYZ.

My question is how to free the memory held by vptr?
shall i do delete vptr or
vptr->Clear() is enough?

(In both the cases the destructor of the XYZ objects are called..)

regards,
Yogesh Joshi

[TB]

yp*********@ind iatimes.com sade:

Hello All,

In my program I am using a pointer to a vector
vector<XYZ> * vptr = new vector<XYZ>;

and also the XYZ class has a char* as one of its member.I have created
all the copy constructor, assignment operator and destructor (The Big
Three ) for XYZ.

My question is how to free the memory held by vptr?
shall i do delete vptr or
vptr->Clear() is enough?

(In both the cases the destructor of the XYZ objects are called..)

regards,
Yogesh Joshi

delete vptr;

will be sufficient.

TB

[Stephan Brönnimann]

If you allocate memory you also should delete it => delete vptr.

Regards, Stephan

[Clark S. Cox III]

On 2006-01-12 08:47:54 -0500, yp*********@ind iatimes.com said:

Hello All,

In my program I am using a pointer to a vector
vector<XYZ> * vptr = new vector<XYZ>;

and also the XYZ class has a char* as one of its member.I have created
all the copy constructor, assignment operator and destructor (The Big
Three ) for XYZ.

My question is how to free the memory held by vptr?
shall i do delete vptr or
vptr->Clear() is enough?

(In both the cases the destructor of the XYZ objects are called..)

Just like any other object that you've allocated via the new operator,
you should delete it when you are finished with it:

delete vptr;

calling vptr-clear() will not delete the vector itself; it will merely
destroy the objects contained within the vector.
--
Clark S. Cox, III
cl*******@gmail .com

[Rolf Magnus]

yp*********@ind iatimes.com wrote:

Hello All,

In my program I am using a pointer to a vector
vector<XYZ> * vptr = new vector<XYZ>;
Why do you allocate the vector dynamically?
and also the XYZ class has a char* as one of its member.I have created
all the copy constructor, assignment operator and destructor (The Big
Three ) for XYZ.

My question is how to free the memory held by vptr?
Just like any other pointer to a dynamically allocated object.
shall i do delete vptr or
vptr->Clear() is enough?

If you mean vptr->clear(), this will only remove all the elements from the
vector. It will not destroy the vector itself.

[sylcheung]

You said "Why do you allocate the vector dynamically?".
Is it a bad practice to do that? If yes, why?

[W Marsh]

On 12 Jan 2006 07:43:14 -0800, "sy*******@gmai l.com"
<sy*******@gmai l.com> wrote:

You said "Why do you allocate the vector dynamically?".
Is it a bad practice to do that? If yes, why?

Because you then have to make sure that it is cleared up properly, and
that the pointer referencing the vector isn't accidentally used
elsewhere, and that when it is used you don't accidentally do
something invalid, and... the list goes on.

If you don't need to use a pointer and dynamic allocation with new and
delete (and believe me, you rarely do) then just don't do it.

[Mike Wahler]

<yp*********@in diatimes.com> wrote in message
news:11******** **************@ g14g2000cwa.goo glegroups.com.. .

Hello All,

In my program I am using a pointer to a vector
vector<XYZ> * vptr = new vector<XYZ>;

and also the XYZ class has a char* as one of its member.I have created
all the copy constructor, assignment operator and destructor (The Big
Three ) for XYZ.

My question is how to free the memory held by vptr?
shall i do delete vptr or
vptr->Clear() is enough?

(In both the cases the destructor of the XYZ objects are called..)

std::vector::cl ear() removes all the vector's elements.
The vector object itself is still there. If you created
it with 'new', you need to destroy it with 'delete'.
This applies to any object created with 'new'.

-Mike

[sylcheung]

But this is the same for "new" any class, not just STL containers. Am I
correctly?

I have a function which go thru a list of Rect ( list<Rect*>), call the
'area' attribute and put that in a vector. Is there a better way to
achieve what I want?

Here is what I did:

template<class T> struct get_area : public unary_function< T, void>
{
get_area(int size) { area = new vector<float>(s ize); }
void operator() (T x) {
area->push_back(x->area);

}

public:
vector<float>* area;
};

vector<float>* getArea(const RectList& rectList) {
int size = rectList.size() ;

get_area<Rect*> p = for_each(rectLi st.begin(), rectList.end(),
get_area<Rect*> ( size ));

return p.area;
}

[Sandeep]

>>yp*********@i ndiatimes.com wrote:

My question is how to free the memory held by vptr?
shall i do delete vptr or
vptr->Clear() is enough?

For memory management there is a concept of smart pointers. boost
library has an implementation of it as well - do have a look at the
concept and the library .. A simple smart pointer can be implemented
very easily....