Beefy Boxes and Bandwidth Generously Provided by pair Networks
good chemistry is complicated,
and a little bit messy -LW
 
PerlMonks  

Comment on

( #3333=superdoc: print w/ replies, xml ) Need Help??
I noticed this a while ago, but didn't really think that much of it at the time. The value, "0E0" evaluates numerically as zero, but is also true. Is this an example of "deep magick" in Perl? I got caught up on this while using the dbi to run some queries. It seems like the whole point (from the docs) was to create a numerical zero, which evaluates to true, so that you can return true (as in a query was successful, didn't cause any errors) but doesn't return any results.

Can anyone confirm or deny this?

on a slightly related note, does anyone know why 0E0 + 1 doesn't stay in scientific notation? It seems counter intuitive to me, but my intuition has been doing funny things lately.

#!perl -w use strict; my $oero = "0E0"; my $zero = "0"; print "oero ($oero) true\n" if($oero); print "oero ($oero) defined\n" if(defined($oero)); print "zero ($zero) true\n" if($zero); print "zero ($zero) defined\n" if(defined($zero)); print "zero eq oero\n" if ($oero eq $zero); print "zero == oero\n" if ($oero == $zero); print "oero+1: ", $oero+1, "\n"; print "oero+zero: ", $oero+$zero, "\n"; print "oero+oero: ", $oero-$oero, "\n"; OUTPUT: oero (0E0) true oero (0E0) defined zero (0) defined zero == oero oero+1: 1 oero+zero: 0 oero+oero: 0

In reply to OEO, a zero that evaluates to true? by coolmichael

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!
  • 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, 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, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • Outside of code tags, you may need to use entities for some characters:
            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.
  • Log In?
    Username:
    Password:

    What's my password?
    Create A New User
    Chatterbox?
    and the web crawler heard nothing...

    How do I use this? | Other CB clients
    Other Users?
    Others avoiding work at the Monastery: (6)
    As of 2014-09-17 00:09 GMT
    Sections?
    Information?
    Find Nodes?
    Leftovers?
      Voting Booth?

      How do you remember the number of days in each month?











      Results (54 votes), past polls