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From: jack@mcvax.uucp (Jack Jansen)
Newsgroups: net.lang.c
Subject: 5<a<50 (was:Additions to C - range checking)
Message-ID: <7000@boring.mcvax.UUCP>
Date: Mon, 30-Jun-86 09:21:51 EDT
Article-I.D.: boring.7000
Posted: Mon Jun 30 09:21:51 1986
Date-Received: Fri, 11-Jul-86 04:58:48 EDT
References: <523@ccird1.UUCP> <155@daisy.warwick.UUCP>
Reply-To: jack@boring.uucp (Jack Jansen)
Distribution: net
Organization: AMOEBA project, CWI, Amsterdam
Lines: 21
Apparently-To: rnews@mcvax

In article <155@daisy.warwick.UUCP> cudcv@daisy.warwick.ac.uk (Rob McMahon) writes:
>In article <523@ccird1.UUCP> rb@ccird1.UUCP (Rex Ballard) writes:
>>
>>if (5<a<50) do_something(a);
>>
>...
>>
>>Is this impossible to parse?
>
>This was in BCPL, and was a GOOD IDEA.

Yes, it is nice from a users standpoint, but if you want to define
the semantics of this operator in a reasonable way, it becomes
difficult. The only way out I see is to let expressions have *two*
values: an ordinary one, and a success/failure indication. Then you
can let the value of 'a<b' be 'b', and the operator return 'success'
when a is less than b. I remember seeing something about a language that
had such semantics, can't remember which one, however.
-- 
	Jack Jansen, jack@mcvax.UUCP
	The shell is my oyster.