Following the maxim of "be strict with your output, but liberal with your input", it is a Best Practice™ to always check, sanitize and normalize your input.

And just for the fun of it: your _lc rewritten into one regex:

use Modern::Perl;

sub _lc {
    my $key = shift;
    my $success = $key =~ s/^-?([^-_]*)[-_]?([^-_]*)$/$2?lc"$1_$2":lc$
+1/e;
    return $key if $success;
}

print _lc($_) while (<DATA>);

__DATA__
content-length
content_length
-content-length
-content_length
Content-Length
Content_Length
-Content-Length
-Content_Length
changed
Changed
-changed
-Changed
Too-many_dashes-Or-underscores

[download]
This sub returns undef (indicating an error) if you give it a string with more than one internal dash or underscore.

CountZero

A program should be light and agile, its subroutines connected like a string of pearls. The spirit and intent of the program should be retained throughout. There should be neither too little or too much, neither needless loops nor useless variables, neither lack of structure nor overwhelming rigidity." - The Tao of Programming, 4.1 - Geoffrey James

My blog: Imperial Deltronics

In reply to Re: On creating hash whose keys aren't case-sensitive by CountZero
in thread On creating hash whose keys aren't case-sensitive by anazawa

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.