You can use reverse on an array or list too, and consequently get the lines to be processed in reverse order:

foreach my $protein ( reverse @protein ) {
    ...

[download]

Or you could use File::ReadBackwards, and do something more like this: 

while( defined( my $protein = $backward_fh->readline ) ) {
    if( ....

[download]

I would probably prefer the latter, because it totally removes the need to slurp the entire file all at once. Maybe that's not an issue for you, but if proteins.txt has the potential of growing really large, line-by-line processing is advantageous.

(Be sure to read the documentation on File::ReadBackwards; I didn't demonstrate instantiating the iterator because it's pretty clear in the POD)


Dave

In reply to Re: Switching the Order of Lines by davido
in thread Switching the Order of Lines by BeckyLynn

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.