This is more than what you asked about, but there are two regexs in the following:

chop (%key_hash = map { split /\s*[|]\s*/,$_,2 } grep (!/^$/,<KEY_FH>)
+);
  ^                             ^  ^  ^    ^ ^            ^      ^
  |                             |  |  |    | |            |      |
  |                             |  |  |    | |            |      + - F
+ile handle
  |                             |  |  |    | |            + - Let only
+ non-empty file lines pass
  |                             |  |  |    | + - Split string into two
+ parts
  |                             |  |  |    + - Default scalar containi
+ng a file line
  |                             |  |  + - Zero or more whitespaces
  |                             |  + - Vertical bar as only member in 
+character set
  |                             + - Zero or more whitespaces
  + - Should be 'chomp' to remove the trailing newlines
[download]

It appears that this code splits a "|" delimited file line into two parts: the first field is the key and the remaining fields are the value. We can give it a try like this:

use strict;
use warnings;
use Data::Dumper;

chomp (my %key_hash = map { split /\s*[|]\s*/,$_,2 } grep (!/^$/,<DATA
+>));

print Dumper \%key_hash;

__DATA__
AAA|B|C|D|E
BBB|G|H|I|J
CCC|1|2|3|4
DDD|6|7|8|9
[download]

The output shows the hash's key/value pairs:

$VAR1 = {
          'CCC' => '1|2|3|4',
          'BBB' => 'G|H|I|J',
          'DDD' => '6|7|8|9',
          'AAA' => 'B|C|D|E'
        };
[download]

Hope this helps!

---

---

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! —

• How do I compose an effective node title?
• How do I post a question effectively?
• Markup in the Monastery

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:
	&		&
	<		&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.