No. The isalpha function I gave returns true only for [a-zA-Z] characters, false on numbers, punctation, international letters, or any other character.

It seems to give the same results for me than lc ne uc: 

sub isalpha {
    no warnings "numeric";
    my($p) = @_;
    0==++$p;
}
sub hasalpha {
    my($s) = @_;
    isalpha(substr($s, 0, 1, "")) and return 1 while
        length($s);
    return;
};
@t = ("f/2", "-2/", "*+)", "165", "foop", "  A=");
$\=$/; $,=" ";
print grep hasalpha($_), @t;
print grep lc ne uc, @t;

[download]

outputs 

f/2 foop   A=
f/2 foop   A=

[download]

This is because if $p is a non-alnum character in the isalpha function, $p++ converts it to a numeric 0 first, than it increases it to 1, so 0==$p++ is false.

In reply to Re^3: Challenge - Creative Way To Detect Alpha Characters by ambrus
in thread Challenge - Creative Way To Detect Alpha Characters by Limbic~Region

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.