Why isn't argv[argc]==(char *)0 ?

[Guy Harris]

>argv has always had an endmarker.  Older versions had the convention 
>that argv[argc] == -1.

*Much* older versions; the first version I saw with argv[argc] == 0 was
V7, from which all modern AT&T-UNIX-derived versions are derived. 
(I.e., unless you have to deal with an archaic UNIX or a Mutant UNIX
>From Hell, you can count on argv[argc] == 0.)