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To: Paul DuBois <dubois@primate.wisc.edu>
Cc: kpneal@pobox.com (Kevin P. Neal), hackers@freebsd.org
Subject: Re: void main
References: <199609040621.BAA29078@night.primate.wisc.edu>
From: Zach Heilig <zach@blizzard.gaffaneys.com>
Date: 04 Sep 1996 02:42:28 -0500
In-Reply-To: Paul DuBois's message of Wed, 4 Sep 1996 01:21:16 -0500 (CDT)
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Paul DuBois <dubois@primate.wisc.edu> writes:

> Um, so what exactly is wrong with void main, other than that you don't
> happen to like it?

Strictly speaking, there are exactly two correct versions of main():

int main(void);

and

int main(int argc, char *argv[]);

Note that "char *argv[]" is exactly equivalent to "char **argv", and
if you leave off the return type, it defaults to int, so these
declarations may look a little different in practice.

You wouldn't write code like:

/* bad.c */
#include <stdio.h>
char *sin(double);

main() { printf("sin(1) == %s\n", sin(1)); }
/* end bad.c */

compile with:

$ cc bad.c -lm

and expect it to work properly.  'int' and 'void' are not compatible
types, just like 'char *' and 'double' are not compatible types.

If you wonder where the other declaration of main() expecting a return
type of 'int' is, remember that something has to call your program
(/usr/lib/crt0.o), and it thinks that main() returns an 'int'.

It is also questionable to gratuitously use undefined behavior (wrt
the ISO C standard) when a 100% correct version costs nothing.

-- 
Zach Heilig (zach@blizzard.gaffaneys.com) | ALL unsolicited commercial email
Support bacteria -- it's the              | is unwelcome.  I avoid dealing
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