rsriram has asked for the wisdom of the Perl Monks concerning the following question:

Hi, I have a numbered list marked up with <nl>...</nl>. All items inside it are marked as <item>...</item>. I want to number these items sequentially, i.e., change the item tag to <item num="1">, <item num="2"> and so on. My code to do this is:

$no++;
$_ =~ s/<item>/'<item num="'.$no.'">'/egs;

In the output file I get the desired numbering but from the start to the end of file, the <item> tags are sequentially numbered. I want the count to restart everytime a new list <nl> is encountered. Any help!!!

Here is my complete code:

if (!@ARGV)
{
   print "\t Usage: perl $0 <filename>\n\n";
   exit(0);
}
open (F1, "<$ARGV[0]") || die ("Can't open the file $ARGV[0]. $!\n");
$out = $ARGV[0];
$out =~ s/(.+)\.(.+)/$1/;
$out = $out.".xml";
open (F2, ">$out") || die ("Can't open the file $out. $!\n");
while(<F1>)
{
   $no++;
   $_ =~ s/<item>/'<item num="'.$no.'">'/egs;
   print F2 $_;
}
close F1;
close F2;

[download]

20060801 Janitored by Corion: Removed by-line <code> tags and enclosed code within one set of <code>...</code> tags

Replies are listed 'Best First'.
Re: Numbering list items
by prasadbabu (Prior) on Aug 01, 2006 at 10:51 UTC

    Hi rsriram,

    Here is one way to do it. But If you have proper xml file it is always good to use XML modules.

    use strict;
use warnings;

my $string = '<nl><item>asdfasdf</item><item>asdfasdf</item></nl><nl><
+item>asdfasdf</item><item>asdfasdf</item></nl>';

$string =~ s|<nl>((?:(?!</nl>).)*)</nl>|'<nl>'.&item($1).'</nl>'|egs; 

print $string;

sub item
{
    my ($item) = @_;
    
    my $no =1;
    
    $item =~ s/<item>/'<item num="'.$no++.'">'/egs;     
    return $item; 
}

output:
-------
<nl><item num="1">asdfasdf</item><item num="2">asdfasdf</item></nl><nl
+><item num
="1">asdfasdf</item><item num="2">asdfasdf</item></nl>

    [download]

    or even shorter than the above 

    $string =~ s|<nl>((?:(?!</nl>).)*)</nl>|my $item = $1; my $no = 1; $it
+em =~ s/<item>/'<item num="'.$no++.'">'/egs;"<nl>$item</nl>"|egs;

    [download]

    Prasad

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Re: Numbering list items
by rodion (Chaplain) on Aug 01, 2006 at 11:00 UTC
    I think you just forgot to reset "$no". Adding the single line 
          $no = 0   if /<n1>/;

    [download]
    at the end of the while loop might do it, if you can rely on the "<n1>" tag not being in the same F1 record as one of your "<item>" tags. If not, you will have to parse things a little finer, as in hsriram's example.
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