Path: utzoo!attcan!uunet!tut.cis.ohio-state.edu!zaphod.mps.ohio-state.edu!usc!elroy.jpl.nasa.gov!decwrl!orc!mipos3!iwarp.intel.com!news
From: merlyn@iwarp.intel.com (Randal Schwartz)
Newsgroups: comp.lang.perl
Subject: Re: Bug or misunderstanding?
Message-ID: <1990Feb27.174836.21449@iwarp.intel.com>
Date: 27 Feb 90 17:48:36 GMT
References: <2860@uvaarpa.virginia.edu>
Sender: news@iwarp.intel.com
Reply-To: merlyn@iwarp.intel.com (Randal Schwartz)
Organization: Stonehenge; netaccess via Intel, Beaverton, Oregon, USA
Lines: 99
In-Reply-To: alfie%cs.warwick.ac.uk@nsfnet-relay.ac.uk (Nick Holloway)

In article <2860@uvaarpa.virginia.edu>, alfie%cs (Nick Holloway) writes:
| [I am sending this via mailing list, since news is a bit dodgy here]
| 
| I am trying to split an array into two arrays. One will contain any
| elements that match any pattern in a pattern array, and the other
| contains all others. Here is the section of code that is causing me
| grief:
| 
| 	@text = ( "Hello", "Joe", "Schmoe", "Gordon" );
| 	@pat = ( "e", "o" );
| 	text: for $text ( @text ) {
| 	    for $pat ( @pat ) {
| 		if ( $text =~ /$pat/i ) {
| 		    print "Match: $pat: $text\n";
| 		    next text;
| 		}
| 	    }
| 	    print "NoMatch: $text\n";
| 	}
| 
| I know that I am using the same name in different contexts, but arrays,
| constants and labels should have a separate namespace (right?).
| 
| The problem seems to be with the "next text;" line. I need that there,
| since otherwise elements may be matched with more than one pattern. I
| can't use a "last;" just to skip the rest of the patterns, coz I need
| to keep elements that do not match. However, the above code does not
| work as expected. Here is the sample output
| 
| 	Match: e: Hello
| 	Match: o: Joe
| 	NoMatch: Schmoe
| 	Match: o: Gordon
| 
| Note that "Joe" did not match on the "e" but on the "o", and "Schmoe" didn't
| match at all!
| 
| Have I misunderstood something vital? This is my first attempt to use
| labelled "next/last"s, and it is possible I have missed something in
| the manual. If so, I am open to suggestions of better ways of doing
| it.  Perhaps if I spell Randal's name wrong, he'll give me a one liner :-) 
| At the moment, I am inclined to think it is a bug.

Well, here's the one-liner (but you spelled my name right):

@hasit = grep(/e/i,@text); @neverhaditneverwill = grep(!/e/i, @text);

I got the same results as you running your code on a Sun3 rev 6.
Your code should have worked (methinks).  Larry?

As a workaround (read: kludge),	 I got the right results with the
following putziness:

@text = ( "Hello", "Joe", "Schmoe", "Gordon" );
@pat = ( "e", "o" );
for $text ( @text ) {
	inner: {
		for $pat ( @pat ) {
			if ( $text =~ /$pat/i ) {
				print "Match: $pat: $text\n";
				last inner;
			}
		}
		print "NoMatch: $text\n";
	}
}

I use labled blocks quite a bit.  Like, for a "loop...end loop"
sorta construct, instead of the C-like idiom of:

	LOOP: while (1) {
		...
		...
		last LOOP if some_condition;
		...
		...
	}

I use:

	LOOP: {
		...
		...
		last LOOP if some_condition;
		...
		...
		redo LOOP;
	}

I guess I don't like to see that funky '1' there when it isn't being
evaluated.  No, I haven't looked at the code to see if it actually got
optimized away.

for (split(/(.)/,"Just another Perl hacker,")) {print if $_;}
-- 
/=Randal L. Schwartz, Stonehenge Consulting Services (503)777-0095 ==========\
| on contract to Intel's iWarp project, Beaverton, Oregon, USA, Sol III      |
| merlyn@iwarp.intel.com ...!any-MX-mailer-like-uunet!iwarp.intel.com!merlyn |
\=Cute Quote: "Welcome to Portland, Oregon, home of the California Raisins!"=/