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- From: vandevod@cs.rpi.edu (David Vandevoorde)
- Newsgroups: comp.std.c++
- Subject: Re: The realloc question: rationale?
- Date: 27 Feb 1996 10:38:40 PST
- Organization: RPI Computer Science
- Approved: austern@isolde.mti.sgi.com
- Message-ID: <xsoohqlz9vu.fsf@pleiades.cs.rpi.edu>
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- X-Original-Date: 26 Feb 1996 23:10:29 -0500
- In-Reply-To: James Kanze US/ESC 60/3/141 #40763's message of 26 Feb 1996
- 11:48:32 PST
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- Originator: austern@isolde.mti.sgi.com
-
- >>>>> "JK" == James Kanze US/ESC 60/3/141 #40763
- <kanze@lts.sel.alcatel.de> writes:
- JK> In article <xsod973w4m5.fsf@glob.cs.rpi.edu> vandevod@cs.rpi.edu
- JK> (David Vandevoorde) writes:
- [...]
- JK> |> Since you can provide your own new operators etc., you can ensure that
- JK> |> it's safe to use realloc with new/delete (or you can provide a function
- JK> |> based on realloc with similar functionality).
- [...]
- JK> 1. It is, in fact, impossible to obtain the address actually returned
- JK> by operator new[]. The implementation is allowed to (and most do) ask
- JK> for extra memory in order to maintain the number of elements.
- JK> Typically, this memory will be in front of the first element, so the
- JK> compiler will `fix up' the address returned by operator new[] before
- JK> you ever see it.
-
- I was aware of that... which is why I didn't claim it was portable :^P
- and suggested ``a function with similar functionality''.
-
- JK> 2. The implementation is allowed to save this address in some sort of
- JK> cache. For example, an alternate implementation of a new expression
- JK> for an array would be for the implementation to maintain an
- JK> associative array of addresses to counts.
-
- That's more troublesome ;-)
-
- Daveed
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