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

Hey everyone I have a quick question on perl, I have a list of files which contain the following tag <NumberofDays>. What I want to do is write a small perl script that would parse those list of files and check the value of that tag, and if the value of that tag is not a number then copy it into a different directory. like eg 
<NumberofDays>23</NumberofDays> this okay leave it
<NumberofDays>Two</NumberofDays> copy this file to a diff dir
<NumberofDays>3d</NumberofDays> copy this file to a diff dir as well

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I hope I explained it clearly

Thanks a bunch for your help

edit (broquaint): fixed formatting

Replies are listed 'Best First'.
Re: Check tag value
by esskar (Deacon) on Apr 08, 2004 at 11:38 UTC
    well, the parsing would be
    m!<NumberofDays>\d+</NumberofDays>!gm;

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    but i belive in Learning By Doing, so why don't u post what you have tried so far solving your problem and we will help you moving you into the right direction.

    bye, bye!
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[d/l]
      This is what I have so far ..I am still working on it 

#!/usr/bin/perl

my $dir = "/tmp/asheesh";
my gdir = "$dir/temp";

opendir (DIR, $dir) or die "can't open dir";
@files = readdir(DIR);
closedir DIR;

foreach $files(@files)
 {
   unless ( $files eq "." || $files eq "..")
     {
        open (FILE, "$files") or die "can't open file";
        @Lines=<FILE>;
        close FILE;
        foreach  $Lines(@Lines)
         {
           chomp $Lines;
           
if ( $Lines eq "<NumberofDays>\d+</NumberofDays>" )

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[d/l]
        Hi, you're code: 
        if ( $Lines eq "<NumberofDays>\d+</NumberofDays>" )

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        should be something like: 
        if ( $Lines =~ m|<NumberofDays>(\d+)</NumberofDays>| )

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        3 differences between your and my line:
        • eq vs. =~
          • to compare against a regular expression you use =~
        • the regular expression is in 'm|' and '|' characters
          • This is to make clear you are using a regular expression
        • the \d+ is in '(' and ')' characters
          • This is used to 'capture' the value of the expression inbetween them. In this case it would capture the value in $1. The rule is the first ()-match is captured in $1, the second in $2 etc. So in your code you could continue with something like 
          print $1

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        Hope this helps getting you started. For documentation on regular expressions there are 2 good tutorials that come with perl that were not mentioned here: perlrequick perlretut
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[d/l]
[select]
        You need a regular expression in your if-test. Start by doing: 
           perldoc perl

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        at a command prompt. You'll notice if you page down a little that there are these 2 perldocs listed for regular expressions: 
           perlre              Perl regular expressions, the rest of the story
   perlreref           Perl regular expressions quick reference

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        So, if you want to read the 1st one, you would do 
           perldoc perlre

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        at a command prompt. The 1st response to your question gave you a regular expression to try. Read the perldocs, try a regular expression, and post back if you still have problems.

        HTH.

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