Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!cs.utexas.edu!execu!sequoia!painter
From: painter@sequoia.execu.com (Tom Painter)
Newsgroups: comp.lang.perl
Subject: Re: Arrays and me :-(
Message-ID: <29248@sequoia.execu.com>
Date: 13 Dec 90 22:54:18 GMT
References: <29144@sequoia.execu.com> <110684@convex.convex.com>
Distribution: usa
Organization: Execucom Systems Corp.
Lines: 66


In article <110684@convex.convex.com> tchrist@convex.COM (Tom Christiansen) writes:
>In article <29144@sequoia.execu.com> painter@sequoia.execu.com (Tom Painter) writes:
>>
>>I'd like to split a passwd file into a multi-dimensional array.
>> [...stuff deleted...]
>
>Let's start out with the basics.  Your very biggest mistake is that
>perl doesn't really and truly have honest-to-goodness first-class 
>multidimensional arrays as you are trying to use them.  You might
>consult question #17 of the FAQ.

I realize this, but apparently you can emulate it with an associative array:

 		$name{$x, $y} = 'Tom';

I suppose that the question was: How do I fill a psuedo-multi-dimensional
array.  Preferably, I'd like to fill it with the output of a split command.
I had hoped that there was a clever Perl (minimalistic) answer.

>Here are some other things:  Remember that perl arrays are by default
>0-based, which makes the GCOS field index 4, not 5.  Also, since you have
>$. as the current line number, there's no need to keep $i.  And when you
>split into @passwd[$i], you're splitting into an array slice of length
>one, which means that everything but the initial field of split is
>discarded, leaving you the login, which you pronounce logname and C
>programmers pronounce pw_name.  Then you say $passwd[5,50], which is
>to your probably surprise really merely asking for element 50 because that
>comma is the C comma operator.  And don't waste time using printf when a
>simple print will do nicely.

Now, I have to wonder why every simple question asked is turned into a
"Let's bash the novice" festival.  My example seemed to be sufficient
to ask the question that I asked.  I'll address the objections.  I
already reset the array base to 1, I suppose that I should've included
that line.  I used (<PASSWD>) for the example, however I'm dealing with
multiple input files so I want to count lines.  Obviously, what I had
was wrong [@passwd[$i]] or I wouldn't have posted the question (No, I
wasn't surprised when it didn't work.).  I'm not a C programmer, so
what they call logname (login, pw_name) is not important to my
question.  The "C comma operator" may be a glaring fact to you but to
me it doesn't mean a thing.  And finally, the printf line was what was
left after I stripped the non-essential portions from the original.
While it could be better in its current use, that's not necessary it
terms of the question.

Now, I think that number of the points are valid in the context of
teaching netreaders the fundamentals of Perl, but I think that the tone
could use some work.  If you want to call me an idiot, send me mail.
But please restrict your posts to helpful suggestions or solutions.  I
have to wonder how many people out there are hesitant to post given the
thrashing that you usually put me through. :-)

BTW, I did pick up a number of helpful hints, once I got past the first
section.  Thanks.

Tom

P.S. Yea, I should've mailed this...
-- 
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Tom Painter                             UUCP: ...!cs.utexas.edu!execu!painter
Execucom Systems Corp., Austin, Texas   Internet: painter@execu.com
(512) 327-7070                                    execu!painter@cs.utexas.edu
Disclaimer: My Company?  They'll claim all my waking hours, not my opinions.
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