We came up with nearly the exact same solution. I believe you can eliminate $val, however, by operating directly on the hash value. 

use strict;
use warnings;

my %hash;
my $id;

while( my $line = <DATA> )
{
    chomp $line;

    # if( $line =~ m/^>(.+?) / )  # changed to \S
    if( $line =~ m/^>(\S+)/ )
    {
        $id = $1;
    }
    else
    {
        $hash{$id} .= $line;
    }
}

[download]

ewijaya, if you are trying to read sequence files in fasta format, you might want to look at bioperl's Bio::SeqIO class.

Update: ihb made a good point about the regex. I made the assumption (based on the example data) that a space will always follow the sequence ID, but that may not always be true. Therefore, ihb's regex is a bit safer for that reason (although you should keep in mind that \w will not match '.' or '-', so \S is probably better).

In reply to Re^2: Concatenating text for a hash problem by bobf
in thread Concatenating text for a hash problem by monkfan

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.