Re: Can auto_ptr<> be used with void and malloc()/free()

From:

"bob" <robert@robert.org>

Newsgroups:

microsoft.public.vc.language

Date:

Tue, 4 May 2010 10:38:37 -0400

Message-ID:

<OIupBe56KHA.5476@TK2MSFTNGP06.phx.gbl>

Thanks to everyone who replied to my post.

It looks like I have to get rid of malloc()/free() or forget about
auto_ptr<> and deal with deallocating memory manually.

For those interested, the reason that I'm using a variable length struct is
that I receive it from a network as a stream of bytes. The first couple of
bytes represent a header and the length of variable size data that follows.
I have a low-level c routine that deals with assembling the packet and then
returns it to clients. Currently the routine allocates ram for the packet
and the client frees it. Quite often logic on the client gets a bit
complicated and ideally I'd like to use auto_ptr<> so I do not need to worry
about freeing the memory allocated in the c routine.

Thanks.

"bob" <robert@robert.org> wrote in message
news:Oid8bru6KHA.3880@TK2MSFTNGP04.phx.gbl...

Hi,

I need to allocate a variable size struct using malloc() and then free it
using free(). Is there a way I could wrap a pointer returned from
malloc() in auto_ptr<>? I've used auto_ptr<> with objects of struct/class
but only when they were allocated using new() operator. AFAIK, it is
generally not safe to allocate with malloc() and then free with delete().

Example:

struct {
int x;
int y;
unsigned char data[1];
} structA;

structA* pa = (structA*) malloc(100);

I'd like to wrap pa pointer in auto_ptr<> so I do not have to worry about
freeing it when I leave a given block.

I think I could do the following:

unsigned char* p = new unsigned char[100];
structA* pa = (structA*) p;
_auto_ptr<unsigned char> ptrA(p);
[...]

Any thoughts?

Thanks.