Path: utzoo!utgpu!attcan!uunet!lll-winken!lll-lcc!ames!mailrus!purdue!decwrl!megatest!djones
From: djones@megatest.UUCP (Dave Jones)
Newsgroups: comp.lang.c
Subject: Re: thanks for "down" answers
Message-ID: <1082@goofy.megatest.UUCP>
Date: 14 Dec 88 20:46:17 GMT
References: <1886@loral.UUCP>
Organization: Megatest Corporation, San Jose, Ca
Lines: 33

From article <1886@loral.UUCP>, by jlh@loral.UUCP (Physically Phffft):

...

> In all his examples he used wait ( (char *) 0).
> I pointed out to him that wait wanted an address in which to 
> stuff a result, and using 0 was probably not a good idea.  His 
> reply was 'thats how it is in my manual', after a few minutes
> of discussion it got upgraded to 'I tried it on my system and it 
> works'. 

Both perfectly valid and correct responces.

From the manual:

     #include <sys/wait.h>

     pid = wait(status)
     int pid;
     union wait *status;

     pid = wait(0)
     int pid;

[Your instructor correctly casts the 0 to a pointer-type, which
the manual omits.]

If you want the status, you pass a non-null pointer and wait
knows what to do.  If you don't want the status, you pass a
null pointer, and wait knows what *not* to do.

To paraphrase Samuel L. Clemmons, I think that you will discover
in couple of years that your instructors have learned quite a bit
in the interim. :-)