On Tue, Aug 05, 2003 at 03:40:42AM +0200, Sebastian Kapfer wrote: > On Mon, 04 Aug 2003 05:00:12 +0200, MJM wrote: > > // change the way it is accessed to prove a point int * p_b = (int *) > > p_a; > > // p_a and p_b point to the same block of dyn. allocated memory; > > Do they? Watch out for inheritance, user-defined casting operators and > other funny stuff. C++ adds a few new meanings to the () casting syntax. > In general, your assumption is _wrong_. > > > // return the memory to free storage using the second pointer delete > > p_b; > > > > I think the free store will be maintained properly because there is a > > control block attached to the allocated block of storage that defines > > the length of the allocated memory. > > No. You have to delete the original pointer (with the original type). > Everything else is undefined behaviour, i.e. it could work, it could leak > memory (completely or partly), it could crash, or even print "42". It > might even work sometimes, and fail mysteriously at other times. Interesting. I figured that the actual allocation/deallocation would end up being handled by a call to malloc() / free(), and free() only cares about having the correct value for the (void *) pointer. Would it not be the case, though, in the barebones example given, that MJM's '_wrong_ assumption' would be correct, and 'it' would work, even if in a more general case it might not? Or would it have been better for C++ to have been named D to stop people wanting to think like this? -- Pigeon Be kind to pigeons Get my GPG key here: http://pgp.mit.edu:11371/pks/lookup?op=get&search=0x21C61F7F
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