Scalar::Util provides access to the underlying Perl API looks_like_number routine which Perl itself uses internally

Perl will evaluate the string (eg) '5621hello' in numeric context as 5621 ... yet looks_like_number() will tell you that the string '5621hello' does not look like a number. That has always struck me as an anomaly .... I tend to think that a a string that "does not look like a number" should evaluate to zero in numeric context, but that (obviously) doesn't always happen. 
use warnings;
no warnings 'numeric';
use Scalar::Util;

$string = '12.3hello';
print Scalar::Util::looks_like_number($string), "\n";

$string *= 2;
print $string, "\n";

__END__

Outputs:
0
24.6

[download]
I don't think this is a big deal, btw - it's just that it doesn't DWIM (for me, anyway).

Cheers,
Rob
Update: I meant to add that this might even have some siginificance for the op - because we can't assume anything about the numeric value of a variable, based on the fact that Scalar::Util says it doesn't look like a number.

In reply to Re^2: is_numeric by syphilis
in thread is_numeric by tlm

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.