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Re: Null Pointer exceptions

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jeff <nospam@nospam.com> writes:

> I've got a large C codebase that frequently triggers bugs where pointers 
> that shouldn't be null, somehow end up getting nulled.
>
> It's easy enough to fix up each individual bug when it gets reported, 
> just by adding a null check:
>
> if
> ((void*) ptr != (void*)NULL)

if (ptr != NULL) is enough.  You don't need the casts.  In fact,
if (ptr) is enough, though some consider that too terse.

> {
>         // existing code that triggered a crash
> }
>
> However, as these null conditions only show up occasionally, there always 
> seem to be more bugs left to find.

This sounds very odd.  You aren't fixing bugs, you are patching up the
effect of bugs.  Putting sticking plasters on a gaping wound comes to
mind.

> My question is: is there a way to deal with all of these problems in one 
> swoop, by ignoring all code that dereferences a null pointer, i.e. null 
> dereference becomes a NO-OP instead of triggering an exception. ?

I don't think should not be considering that sort of thing at all.
There is almost certainly some other underlying problem that needs to be
fixed.  The pointers should not be null, you say, and you don't know why
they become null, so that's where the effort needs to go -- finding out
why, and stopping it.

-- 
Ben.

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Thread

Null Pointer exceptions jeff <nospam@nospam.com> - 2015-04-22 21:34 +0000
  Re: Null Pointer exceptions James Kuyper <jameskuyper@verizon.net> - 2015-04-22 18:02 -0400
    Re: Null Pointer exceptions Stephen Sprunk <stephen@sprunk.org> - 2015-04-22 18:30 -0500
      Re: Null Pointer exceptions James Kuyper <jameskuyper@verizon.net> - 2015-04-22 19:44 -0400
        Re: Null Pointer exceptions Stephen Sprunk <stephen@sprunk.org> - 2015-04-23 11:53 -0500
          Re: Null Pointer exceptions Richard Heathfield <rjh@cpax.org.uk> - 2015-04-23 18:59 +0100
  Re: Null Pointer exceptions Barry Schwarz <schwarzb@dqel.com> - 2015-04-22 15:17 -0700
    Re: Null Pointer exceptions James Dow Allen <gmail@jamesdowallen.nospam> - 2015-04-23 04:11 +0000
  Re: Null Pointer exceptions Robert Wessel <robertwessel2@yahoo.com> - 2015-04-22 17:19 -0500
  Re: Null Pointer exceptions Ben Bacarisse <ben.lists@bsb.me.uk> - 2015-04-22 23:46 +0100
  Re: Null Pointer exceptions Nobody <nobody@nowhere.invalid> - 2015-04-23 03:14 +0100
    Re: Null Pointer exceptions James Kuyper <jameskuyper@verizon.net> - 2015-04-23 12:32 -0400

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