Pointer if test for for NULL

[Chris Johns]

Hello,

The Austin Group (Open Group) has been having a discussion about NULL 
meaning all bits 0 [0][1]. For example:

  struct s* p;
  p = malloc (sizeof (struct s));
  if (p)
    memset (p, 0, sizeof (*p));

The issue raised is "If 'struct s' contains a pointer is the pointer 
initialised to NULL correctly ?". This is not what I wish to discuss.

Considering this I am wondering if the 'if (p)' code is strictly valid ?

Does this code also imply false happens if NULL is all bits 0 ?

Should this code be changed to:

  if (p != NULL)

I am guilty of coding the if's this way and I am wondering if this 
should be changed.

Chris

[0]
https://www.opengroup.org/sophocles/show_mail.tpl?CALLER=show_archive.tpl&source=L&listname=austin-group-l&id=13687
[1]
http://groups.google.com/group/comp.lang.c/browse_thread/thread/0977fba3ad06cd27/059969c527e8bc04