Hi Monks,

I have a function with should select files by a given list of extension. I wrote a program, which did not work. After playing a little around I found a working solution (using a local variable: my $x). But I do not understand, why my first version is not working.

Can you help me explaining the difference between this two versions:

In the first version the expression(@ext) is replaces by '1';

In the second version the expression(@ext) is correct. ('f.*\\.txt$', 'f.*\\.txt.*$')

Thanks for your help !!!


use strict;
use warnings;
use Data::Dumper qw(Dumper);
$\="\n"; 

my @ext;
my @list=('f1.txt','f2.txtx','f3.xtxt','x1.txt');
my  $ex="f*.txt,f*.txt*";

print " Version 1: Not working--------------------------------";
@ext=map { $_=quotemeta($_).'$'; s/\\\*/.*/;} split(/,/,$ex);         
+  # <<<<<< compare this line
print "qr=".Dumper(\@ext);
foreach my $e(@ext)
{ foreach my $f(@list) {print "Match: ($e) => $f" if ($f=~m/$e/); }}

print " Version 2: working--------------------------------";
@ext=map { my $x=quotemeta($_).'$'; $x=~s/\\\*/.*/g; $_=$x;} split(/,/
+,$ex);  # <<<<<< compare this line
print "qr=".Dumper(\@ext);
foreach my $e(@ext)
{ foreach my $f(@list) {print "Match: ($e) => $f" if ($f=~m/$e/); }}

[download]

In reply to Why do I need a local variable in map function by Anonymous Monk

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.