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From: marty@ism780c.UUCP (Marty Smith)
Newsgroups: net.lang.c,net.lang.pascal
Subject: Re: Pascal vs C, again (was: Pascals Origins)
Message-ID: <2943@ism780c.UUCP>
Date: Mon, 21-Jul-86 12:05:42 EDT
Article-I.D.: ism780c.2943
Posted: Mon Jul 21 12:05:42 1986
Date-Received: Wed, 23-Jul-86 09:27:10 EDT
References: <2222@brl-smoke.ARPA> <7014@boring.mcvax.UUCP> <3130@utcsri.UUCP>
Reply-To: marty@ism780c.UUCP (Marty Smith)
Organization: Interactive Systems Corp., Santa Monica, CA
Lines: 47
Xref: watmath net.lang.c:10013 net.lang.pascal:593

In article <3130@utcsri.UUCP> greg@utcsri.UUCP (Gregory Smith) writes:
>
>Challenge: given
>
>var	x: array [1..1000] of integer;
>
>write a code fragment to find the location of the first 0 in x. The
>condition that no zeroes exist must be distinguished.
>
>Further rules:
>	- Standard Jensen & Wirth Pascal ( no break from loop )
>	- *** x[i] must not be evaluated for i<1 or i>1000 ***
>	- The search loop must be terminated as soon as a zero is found.
>	- 'a or b', 'a and b' always evaluate both a and b ( I think
>	   this is a rule in Jensen & Wirth )
>
>This is the best I can find:
>	var i: integer;
>	...
>	i :=1 ;
>	while i<1000 and x[i] <> 0 do
>		i := i+1;
>	if x[i] = 0 then writeln('zero at location', i )
>	else writeln('not found');
>
>weird,huh? Note that the condition 'x[i]=0' is evaluated twice ( once
>in the negative sense ), which would be unacceptable if we were searching
>an array of records and the test was expensive.
>
What's wrong with this one?

	label 1,2;
	var i: integer;
	...
	i :=1 ;
	while i<=1000 do
		if x[i] = 0 then goto 1
		else i := i+1;

	writeln('not found');
	goto 2;
1:      writeln('zero at location', i )
2:      ...



		  Martin Smith