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Date: Sun, 3 Sep 2000 19:04:09 +0100
From: Mark Ovens <marko@freebsd.org>
To: questions@freebsd.org
Subject: perl(1) question
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Does index() ignore leading whitespace? A perl(1) script I have
appears to be doing just that. Isolating the relevant lines I have:

#!/usr/bin/perl -w

open 'CONTENTS',"/usr/mark/scrap" or die "cannot open /usr/mark/scrap";

until (eof 'CONTENTS') {
    chomp ($line = <CONTENTS>);
    $i = index($line, /FOO/i); 
    print "line\=$line\n";
    print "i \= $i\n";
};

close 'CONTENTS';

Running this on a file containing:

Foobar
 Foobar
  foobar
   FOOBAR
	foOBar

I get:

# ./scrap.pl scrap
Use of uninitialized value at ./scrap.pl line 7, <CONTENTS> chunk 1.
line=Foobar
i = 0
Use of uninitialized value at ./scrap.pl line 7, <CONTENTS> chunk 2.
line= Foobar
i = 0
Use of uninitialized value at ./scrap.pl line 7, <CONTENTS> chunk 3.
line=  foobar
i = 0
Use of uninitialized value at ./scrap.pl line 7, <CONTENTS> chunk 4.
line=   FOOBAR
i = 0
Use of uninitialized value at ./scrap.pl line 7, <CONTENTS> chunk 5.
line=   foOBar
i = 0
#

So index() appears to be ignoring the leading whitespace because it
always returns 0.

Also, what causes the "Use of uninitialized value...." warning? I
cannot see anything wrong with the script. I've checked Learning Perl
by Schwartx and Christiansen and the perl manpages; also the code is
taken from the original script which doesn't give this warning.

Any pointers would be greatly appreciated.

TIA

-- 
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