But you do have to worry if you for some reason call 'each' or 'keys' on a hash in an inner loop of an each loop. There is not really any way around this expect to use 'keys' in your outer loop instead of 'each'. 
# this code creates an endless loop
my %hash = (
  foo=>"x",
  Foo=>"y",
  Bar=>"a",
  bar=>"c"
);
while(my($key,$value)=each %hash){
   # dumb example 
   for my $key2 (keys %hash){
       if(lc($key) eq lc($key2)){
         print "key $key is similiar to $key2\n";
       }
   }
}

[download]

In reply to Re^2: The Anomalous each() by fletcher_the_dog
in thread The Anomalous each() by jdhedden

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.