VC Language - How does "delete" work?

Author

How does "delete" work?

Boki

2006-05-30, 4:14 am

Hi All,
How does "delete" work?

Does that equal to

i_Boki = null;

?

Best regards,
Boki.

Marcus Heege

2006-05-30, 4:14 am

Hi Boki

"Boki" <bokiteam@ms21.hinet.net> wrote in message
news:1148982536.196077.138310@j33g2000cwa.googlegroups.com...
> Hi All,
> How does "delete" work?
>
> Does that equal to
>
> i_Boki = null;
>
> ?
>
> Best regards,
> Boki.

delete is a language construct that ensures that a) the destuctor of an
object is called and b) the memory of an object is made available for other
memory allocations.

In theory, you can implement the memory allocation/deallocation logic
manually by overloading operators new and delete, but in most cases, you
will use the default implementation provided by the CRT.

Marcus

Ulrich Eckhardt

2006-05-30, 8:08 am

Boki wrote:
> How does "delete" work?

Delete first invokes the object's destructor and then releases the
associated storage.

> Does that equal to
>
> i_Boki = null;
>
> ?

Does what exactly equal to this?

In case you want to learn C++, this is not the right place, just a support.
Pick a good book from the reviews section on accu.org.

Uli

Alex Blekhman

2006-05-30, 8:08 am

Boki wrote:
> Hi All,
> How does "delete" work?
>
> Does that equal to
>
> i_Boki = null;

No, operator delete does not affect pointer value at all. It
aims at object(s) that pointer points to. Operator delete is
symmetric to operator new:

X* px = new X; // C++ statement

This is what compiler does behind the scenes:

X* px = malloc(sizeof(X)); // allocate enough memory for X
X::X(px); // call X constructor to create object instance

Deleting with operator delete:

delete px; // C++ statement

This is what compiler does behind the scenes:

if(px)
{
X::~X(px); // call X destructor to destroy object
instance
free(px); // free memory
}

HTH
Alex

Arman Sahakyan

2006-05-30, 8:08 am

Hi,

"Boki" wrote:

> Hi All,
> How does "delete" work?
>
> Does that equal to
>
> i_Boki = null;
>
Never!

delete is applicable to a pointer which is pointing an object within the heap.
IOW, if an object is created by 'new', it should be destroyed by 'delete'.
Afterwards, you may assign NULL to the deleted object's pointer (which is
encouraged to do).

--
======
Arman

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