Heres a not very tight implementation, but it should make clear whats going on: 
{
    my %hash = (
        'Ask'   =>  1,
        'Bob'   =>  1,
        'Cat'   =>  1,
        'amy'   =>  1,
        'ben'   =>  1,
        'can'   =>  1,
    );

    print join "\n", sort case_sorter keys %hash;
}

sub case_sorter {

    my $first_a = substr $a, 0, 1;
    my $first_b = substr $b, 0, 1;

    if ( ($first_a eq uc($first_a)) && ($first_b eq uc($first_b)) ) {
        return $a cmp $b;
    }
    elsif ( $first_a eq uc($first_a) ) {
        return 1;
    }
    elsif ( $first_b eq uc($first_b) ) {
        return -1;
    }
    else {
        return $a cmp $b;
    }
}

[download]

In reply to Re: Sorting - lower to upper by shemp
in thread Sorting - lower to upper by joule

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.