🚀 go-pugleaf

Martijn Lievaart <mlievaar@orion.nl> wrote in article
<6c1628$lmg$1@news2.xs4all.nl>...
> 
> Trenton D. Adams wrote in message ...
> >If I make a pointer in C++, say to an object!  I initialized this
pointer
> >to point to a place in memory created by the new function.  Will this
> >area in memory be release when the object is destroyed, or do I have to
> >explicitely have to call delete?
> >
> 
> *If* using new you must use delete. This is the approved way of
destructing
> an object. It is possible to call an destructor directly, but this is
only
> needed in very very rare circumstances and always in conjunction with a
new
> with a placement. Don't do this if you're not sure what you're doing, and
> from your question I can gather you're not.
> 
> On the other hand, for objects not allocated by new (that is globals or
> automatic (stack) objects), you never have to worry about destruction.
The
> object is destructed when it goes out of scope.
> 
> Maybe the following code fragments help:
> All code fragments assume "class A {};" defined.
> 
> 1)
> void f() {
>     A a();
> }                // <- a gets destructed here
> 
> 2)
> void f() {
>     A *a = new A;
> }                // <- memoryleak, a never destructed
> 
> 3)
> void f() {
>     A *a = new A;
>     delete a;
> }                // OK
> 
> 4)
> A *pa;
> void f() {
>     A a();
>     pa = &a;
> }                // a gets destructed here, pa points to never never
land,
> don't use anymore.
> 
> 5)
> void f() {
>     A a();
>     A *pa;
>     pa = &a;
>     delete pa;    // BAD! Never delete an object not allocated by new!!!!
> }
> 
> 
> 
> 

There is one case not covered above (a not so rare exception):

void f() {
	CWnd * wnd = new CWnd;
	wnd -> Create (...);
...
	wnd -> DestroyWindow ();
	// do not delete wnd; because it is deleted in DestroyWindow!
	// moral: RTFM.
}

My $.02 worth,
Will McKee.

-- 
---------------------------------------
William A. McKee
wamckee@cjkware.com
http://www.cjkware.com