Note that scalar(%h) can be unreliable for tied hashes, especially prior to 5.8.3. Before then, the result usually depended on the content of the hash before it was tied (which means it would typically be false). Beginning in 5.8.3, if a SCALAR method is supplied, the result will be whatever that returns. Without SCALAR, perl makes a guess about whether the hash has content and returns a simple true or false, with the idea that at least if (%h) should work where possible. (The only case where this guess is wrong is if you've iterated through the hash with each() and deleted every returned key, but not yet gotten an undef from each().)

In reply to Re: Effect of scalar function on hash by ysth
in thread Effect of scalar function on hash by bowei_99

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.