Re: Setting pointer to null!

On Wed, 1 Apr 2009 21:51:39 +0100, "David Webber"
<dave@xxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:

The "= NULL" is technically superfluous, (if you get the code right), but
if you make a mistake afterwards and forget to assign x in one path through
the program, this makes it MUCH clearer where to look when you're debugging.

But if your code contains a subsequent comparison against NULL, you still
have a logic error.

A debug build would assign it NULL anyway

Actually, debug builds do not and AFAIK have never done that.

so why not make life eaier for
yourself and initialise it NULL on a release build. Then when it crashes
you'll know what to look for.

The best thing is to assign a non-NULL singular value. That's what debug
builds do, and I think they use a repeated 0xCD pattern. There are several
such patterns, and they are documented in MSDN somewhere. What would really
be cool is if the compiler generated extra code to disallow comparing two
such pointers, doing arithmetic on them, etc, which would make it more
foolproof. In any case, if you "defensively" initialize all pointers to
NULL, you defeat this debugging feature! For this reason, and the one
mentioned earlier, I don't believe in this sort of "defensive programming",
if that's the proper term for it.

--
Doug Harrison
Visual C++ MVP
.

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