Article View: net.lang.c
Article #9333Re: char vs. int in arg decls
From: Chris Torek
Date: Tue, 16 Sep 1986 20:07
Date: Tue, 16 Sep 1986 20:07
52 lines
1944 bytes
1944 bytes
From: Rick Genter <rgenter@labs-b.bbn.com>
Yes, it will work to interchange (int) and (char) as the
types of function arguments, as long as you *never* use &,
or *only* work on VAXen (and similar-endian machines).
It will work at other times as well.
I tried to port [code like the below] to the Sun.
add_char_to_line (':'); /* draw border */
add_char_to_line (c)
{ /* no decl for c, so default to int */
<...>
ins_char_in_buffer (& c, & buf);
}
ins_char_in_buffer (cp, bufp)
char *cp;
BUF *bufp;
{
<...>
}
This code is wrong, and lint will say so. It is wrong not because
':' is an int, and add_char_to_line's parameter is therefore int,
but because add_char_to_line's parameter is declared as an int and
its address (type `int *') is passed to a function expecting type
`char *'. Were add_char_to_line declared as
add_char_to_line(c)
char c;
{
...
ins_char_in_buffer(&c, &buf);
}
the code would have been correct (even though the call to
add_char_to_line above passes ':', which has type `int': this is
another place where automatic promotion has odd effects).
Dennis would have liked this guy; I said "lint" to him and
he replied "?" :-).
Actually, I believe `?' is due to Kernighan. (Anyone at You Know
Where care to comment?)
--
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 1516)
UUCP: seismo!umcp-cs!chris
CSNet: chris@umcp-cs ARPA: chris@mimsy.umd.edu
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Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: arc1-ca.pugleaf.net!utzoo!mnetor!seismo!brl-adm!brl-smoke!smoke!chris@mimsy.umd.edu From: chris@mimsy.umd.edu (Chris Torek) Newsgroups: net.lang.c Subject: Re: char vs. int in arg decls Message-ID: <3877@brl-smoke.ARPA> Date: Tue, 16-Sep-86 16:07:05 EDT Article-I.D.: brl-smok.3877 Posted: Tue Sep 16 16:07:05 1986 Date-Received: Sat, 20-Sep-86 00:31:15 EDT Sender: news@brl-smoke.ARPA Lines: 52