Newsgroups: comp.lang.c
Path: utzoo!henry
From: henry@utzoo.uucp (Henry Spencer)
Subject: C++ and ANSI C
Message-ID: <1989May4.001911.3382@utzoo.uucp>
Organization: U of Toronto Zoology
References: <12005@paris.ics.uci.edu> <44100029@hcx2>
Date: Thu, 4 May 89 00:19:11 GMT

In article <44100029@hcx2> daver@hcx2.SSD.HARRIS.COM writes:
>From "Computerworld" (4/24/89, p. 31):
> "... A key selling point of C++ is its relationship with the established C
> language.  It includes ANSI-standard C as a subset, as does Objective C, ..."
>
>Perhaps statements like the above cause the confusion...

Quite likely, since they're not true.  There are a couple of fundamental
incompatibilities between C++ and C (ANSI or not), plus a number of minor
ways in which ANSI C differs from C++ in areas where they overlap.  Most
of the latter will go away when Bjarne's crew gets the new official C++
reference manual out the door, but at the moment ANSI C is *not* a subset
of C++, even if you ignore the big incompatibilities.  Computerworld, as
usual, basically doesn't know what it's talking about.

To break the suspense, the two big incompatibilities are:

1. "extern foo();" means (so to speak) "extern foo(...);" in ANSI C and
	"extern foo(void);" in C++

2. declaring a struct or union tag in C++ essentially does an implicit
	typedef on that identifier as well
-- 
Mars in 1980s:  USSR, 2 tries, |     Henry Spencer at U of Toronto Zoology
2 failures; USA, 0 tries.      | uunet!attcan!utzoo!henry henry@zoo.toronto.edu