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

[Chris Torek]

In article <828 at ruso.UUCP> wolfgang at ruso.UUCP (Wolfgang Deifel) writes:
>I think it's a difference if you write " NULL + 1 " ( which is non-
>portable C, NULL is a machine dependent macro ) and " strchr(...) + 1 ".

There is a difference.  However:

>strchr() is a function that returns always a legal value. If strchr fails
>it will return (char*)0 ( regardless of the machine or the compiler ),
>and here it's legal to add '1' ( the result is (char*)1 ).

this is what we just got finished saying is false: it is NOT legal to
add 1 to (char *)0; indeed, it is not legal to add 1 to any of the
various infinite varieties of nil pointer.
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7163)
Domain:	chris at mimsy.umd.edu	Path:	uunet!mimsy!chris