"do ... while ((NULL + 1) - 1);" -- valid C?

[Robert A. Earl]

In article <696 at ftp.COM> wjr at ftp.UUCP (Bill Rust) writes:
>In article <10684 at smoke.BRL.MIL> gwyn at brl.arpa (Doug Gwyn) writes:
>>In article <961 at virtech.UUCP> cpcahil at virtech.UUCP (Conor P. Cahill) writes:
>>>NULL + 1 is a valid operations, ...
>>No!
>In my experience, NULL is always defined using the preprocessor line
>"#define NULL 0" (or 0L). Since the while construct is relying on the
>fact NULL is, in fact, 0, doing NULL + 1 - 1 is ok.
>Bill Rust (wjr at ftp.com)


I have to disagree with Bill here.  The NULL being
returned was from a string manipulation function...ie
not just a NULL but a (char *) NULL....I believe it is
illegal (or at least unportable) to add (char *)NULL + 1.


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