Xref: utzoo comp.arch:2979 comp.lang.c:5735
Path: utzoo!mnetor!uunet!husc6!cmcl2!brl-adm!umd5!mimsy!chris
From: chris@mimsy.UUCP (Chris Torek)
Newsgroups: comp.arch,comp.lang.c
Subject: Re: C machine
Message-ID: <9907@mimsy.UUCP>
Date: 20 Dec 87 21:52:29 GMT
References: <261@ivory.SanDiego.NCR.COM> <164@sdeggo.UUCP> <3078@phri.UUCP>
Followup-To: comp.lang.c
Organization: U of Maryland, Dept. of Computer Science, Coll. Pk., MD 20742
Lines: 39

[I am moving this to comp.lang.c]
>In article <164@sdeggo.UUCP> dave@sdeggo.UUCP (David L. Smith) writes:
>>Besides, there's nothing that says you can't write a string package which
>>has the string preceeded by the length.

It is not hard, but it is annoying:

In article <3078@phri.UUCP>, roy@phri.UUCP (Roy Smith) writes:
>... the problem is that the C compiler only supports null-terminated
>string constants (of the form "I am a string").  Either you have to
>learn to live without string constants, or put up with having to
>initialize everything with 'cvt_null2count ("string constant")' at run time.

The following works:

	typedef struct string {
		int	s_len;
		char	*s_str;
	} string;
	#define	STRING(x) { sizeof(x) - 1, x }

	string foo = STRING("this is a counted string");

Unfortunately, some compilers (including 4BSD PCC) then generate
the string twice in data space, and the `xstr' program only makes
it worse.  In addition, since automatic aggregate initialisers are
not permitted, and there are no aggregate constants, automatic data
must be initialised with something like this:

	f()
	{
		static string s_init = STRING("initial value for s");
		string s = s_init;
		...

(I believe the dpANS allows automatic aggregate initialisers.)
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7690)
Domain:	chris@mimsy.umd.edu	Path:	uunet!mimsy!chris