Re: array allocaton size

From: Victor Bazarov (v.Abazarov_at_comAcast.net)
Date: 06/25/04 

Date: Fri, 25 Jun 2004 14:11:26 GMT

Keith S. wrote:
> This may be a dumb question, but I've searched the FAQ
> and can't find an obvious answer...
>
> Let's say I have a class e.g.
>
> class fred
> {
> public:
>
> int x;
> int y;
> };
>
> then I create an array of fred:
>
> freds = new fred[2];
>
> Now, I'd expect to have allocated 8 bytes * 2 i.e. 16 bytes.

Is that 'sizeof(fred) * 2'?

> However, if I step through the code with a debugger I see
> that operator new is getting called with a size of 20 bytes.
> Why is this? What's the extra 4 bytes coming from?

Some compiler-/OS-specific dynamic memory allocation information
is stored there, perhaps. Why do you care?

> The platform is VC++ .NET 2003 in debug mode if it makes any
> difference...

You might want to ask in microsoft.public.vc.language if you need
to know more about VC++'s memory manager.

V

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