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Date: Wed, 04 Sep 1996 07:24:50 -0400
To: Zach Heilig <zach@blizzard.gaffaneys.com>
From: "Kevin P. Neal" <kpneal@pobox.com>
Subject: Re: void main
Cc: Paul DuBois <dubois@primate.wisc.edu>, hackers@freebsd.org
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At 02:42 AM 9/4/96 -0500, Zach Heilig wrote:
>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'.

Right. Resulting in random numbers being returned to the shell.

I got tired of typing m68kasm -l filename.s, and put it into a makefile.
Typed 'make', and got a "Fatal Error [put random number here]" message
even though there was no error. The error was "void main()".

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

Bingo.
--
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