From:	Chris Mears <cmears AT bigpond DOT com>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: getch() mysteriously defined
Organization:	only if absoultely necessary
Message-ID:	<8ubbmsk17t4djl7cp8mput3su30k9uebk5@4ax.com>
References:	<8k470e$262$1 AT plato DOT wadham DOT ox DOT ac DOT uk>
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Date:	Fri, 07 Jul 2000 20:26:51 +1000
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To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp
Reply-To:	djgpp AT delorie DOT com

On 7 Jul 2000 10:13:50 +0100, that hoopy frood J-P scribbled the
following:

>Does anyone know why this program works "as-is" i.e. with no extra
>pre-compiler #include lines:
>
>/*---------------------------*/
>
>int main()
>{
>  getch();
>}
>
>/*---------------------------*/
>
>If getch() is declared in conio.h (I think it's in grx20.h as part of the
>GRX library, too), then how on earth can gcc under rhide compile the
>program, and run it, and return the code of the keypress, without some
>header file or other?

Well, gcc *does* complain:

proto.c: In function `main':
proto.c:3: warning: implicit declaration of function `getch'
proto.c:4: warning: control reaches end of non-void function

In C, it was legal to call a function without a prototype, or even a
declaration(?).  If a declaration is omitted, the compiler assumes
that the function has a return value of type int and takes a fixed
number of arguments.

The new standard for C disallows this.  C++ has never allowed it.

getch() is still called because it is part of libc, and libc is linked
with the executable.

-- 
Chris Mears
ICQ: 36697123

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