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From: danw@tekchips.LABS.TEK.COM (Daniel E. Wilson)
Newsgroups: comp.lang.c
Subject: Re: C++ and ANSI C
Message-ID: <3934@tekcrl.LABS.TEK.COM>
Date: 4 May 89 21:02:48 GMT
References: <12005@paris.ics.uci.edu> <44100029@hcx2> <1989May4.001911.3382@utzoo.uucp>
Sender: ftp@tekcrl.LABS.TEK.COM
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In article <1989May4.001911.3382@utzoo.uucp>, henry@utzoo.uucp (Henry Spencer) writes:
> 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, ..."
> 
> 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
> -- 

    Number 1 is incorrect since C++ uses '...' to indicate that the number
and type of arguments is unknown.  The void keyword in ANSI C indicates
that the function takes no arguments.  No arguments in the prototype in
C++ means that there are no arguments.

    Number 2 is correct since the struct and union concepts in C++
are subsets of the class concept.  The class concept requires that
a class be a new data type.

Dan Wilson