NULL etc.

[Sean Levy]

Here's part of what I do:

    #define NIL(t) ((t *)0)     /* might change to some strange */
                                          /* number for the 48-bit datapath
HP's :-) */
    #define NULL NIL(char) /* for backwards compatibility */

Then, f'rinstance

    struct hostent *hp;

    hp = gethostbyname(argv[1]);
    if (hp == NIL(struct hostent)) /* call lost */
     ...

I find this much easier to read. I don't write NULL in code anymore,
I use NIL(char). Being a combo Lisp/C programmer, NIL makes
more sense to me as a name for the pointer that points at nothing
than NULL does. I type fast enough that I don't really make an issue
of having to type an extra 5 characters to get what everyone seems to
call a "NULL pointer" on this list. I would add that distinctions between
0 and a pointer become VERY important at a place like CMU, where
code may be compiled on RT's, Suns, uVaxen and god knows what
else. The above #define's go in a header file called "basic.h" on my
personal include path. I only include <stdio.h> in modules that, well,
do I/O. I'm also going to switch completely to C++ verrrry soon...

  Sean Levy
  Engineering Desingn Research Center (EDRC), CMU
  Internet: snl @ cs.cmu.edu
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