Path: utzoo!attcan!uunet!aplcen!haven!adm!smoke!gwyn
From: gwyn@smoke.BRL.MIL (Doug Gwyn)
Newsgroups: comp.unix.wizards
Subject: Re: Implementing NULL trapping
Message-ID: <13323@smoke.BRL.MIL>
Date: 9 Jul 90 11:52:45 GMT
References: <412@minya.UUCP> <1990Jul5.174608.17336@eci386.uucp> <423@minya.UUCP>
Organization: U.S. Army Ballistic Research Laboratory, APG, MD.
Lines: 14

In article <423@minya.UUCP> jc@minya.UUCP (John Chambers) writes:
>I've also used this on occasion to illustrate the Old Engineer's
>maxim that you can't guarantee the correct functioning of a system
>by guaranteeing correctness of all its parts.

Sure you can, if the design is also correct.

However, in this particular example, the C implementation was
clearly NOT correct, since the implementors assigned an object
an address such that it was not distinguishable from a null
pointer.

There is no way to guarantee that one's application will not
break due to bugs in the implementation of the target system.