Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!taumet!steve
From: steve@taumet.com (Stephen Clamage)
Newsgroups: comp.lang.c++
Subject: Re: Mixing C and C++
Message-ID: <670@taumet.com>
Date: 15 Apr 91 16:12:54 GMT
References: <72092@brunix.UUCP>
Organization: Taumetric Corporation, San Diego
Lines: 33

sdm@cs.brown.edu (Scott Meyers) writes:

>Suppose I'm writing a program in both C and C++, and I've got globals
>requiring compile-time initialization in both.  Then both languages will
>want to own "main" (i.e., have main written in their language).  Is there a
>nice way to solve this problem...

>I assume that both languages generate a routine "real_main"...
>However, only one real_main() will get called, the one belonging to
>whichever language writes main.  Is there a portable solution?

What you describe is common in implementations of C++, but does not
usually apply to C.  C++ allows specification of runtime code to
be executed (conceptually) before main(), and (conceptually) after
main() exits.  C provides no such facility to the C programmer, and
it is unusual for a C compiler to require that main() be compiled by
that C compiler (but some have that requirement for other reasons).

If you use a C++-to-C translator, it is usually packaged to work
with a particular C compiler (or any of a group), and you just
write main() in C++.  The C compiler sees main(), and does whatever
it needs to do with it.

Of the C++ object-code compilers I am familiar with, all provide a
companion C compiler, and none have any requirement on main() that
would prevent mixing C and C++ code.  Some C++ object-code compilers
do not even require main() to be written in C++.

So: is your question theoretical, or do you actually have separate C and
C++ compilers which each require main() to be compiled by that compiler?
-- 

Steve Clamage, TauMetric Corp, steve@taumet.com