Some reading that might make this behavior more clear is Scalar values from perldata.

In order to have its ability to silently work with strings, numbers and booleans without explicit coding of intent, Perl actually stores appropriate values internally. When you use the expression $var = !$var;, you set the variable to FALSE and clear out any numbers or strings associated with it. When you then ask it to print $var, Perl checks what it knows about the value. Since you want a string and the value is FALSE, it outputs "", the false string. Hence, after toggling, you actually have @array = ('1', '', '1'); You can get your expected behavior if you numify, for example with the code $_ += 0 foreach @array;. This will tell Perl to store a numerical value, which it will check before output.

As a side note, you should pick visible characters as delimiters when checking what you are actually outputting. If you'd used print "<$_>"; for example, you would have gotten the much more obvious <1><><1> as output.

In reply to Re: Logical Not not working!!! by kennethk
in thread Logical Not not working!!! by baski

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.