In addition to japhy's reference, you may find these helpful:

• The relevant section in perlfaq4. (Try perldoc perlfaq4 to read your local copy.)
• Recipe 2.1 in The Perl Cookbook (aka the Ram book)
• How to identify a number datatype in a string?
• Number?
• Validating Numbers in CGI Script?
• Checking whether a $var is a number
• Tom Christiansen's thoughts on the subject.
  (tilly and MeowChow refer to this article in the earlier threads, but the link they used is now out-of-date. This is its current location.)

--f

_____________________________________________________
Jeff[japhy]Pinyan: Perl, regex, and perl hacker.
s++=END;++y(;-P)}y js++=;shajsj<++y(p-q)}?print:??;

use Regexp::Common;

while (<>) {
    /$RE{num}{real}/                and print q{a number\n};
    /$RE{quoted}/                   and print q{a ['"`] quoted string\
+n};
    /$RE{delimited}{-delim=>'/'}/   and print q{a /.../ sequence\n};
    /$RE{balanced}{-parens=>'()'}/  and print q{balanced parentheses\n
+};
    /$RE{profanity}/                and print q{a #*@%-ing word\n};
}
[download]

In addition to this, Regexp::Common allows the specification and matching of {real} and {int} numbers, numbers of differing base and those separated into groups by a specified separator.

Definitely worth a look at ... TheDamian++

perl -e 's&&rob@cowsnet.com.au&&&split/[@.]/&&s&.com.&_&&&print'

You are using some indenting. But it is deceptive -- the indenting doesn't correspond to what you are doing. And several aspects of your logic would be much clearer with the help of some indenting that made the flow of your code clear.

Finally, and in answer to your question, here is a slightly re-worked version of your code that does what you want. Note that I also put in a feedback line for the 0-99.99 test that you do.

my $length = 0;
while (1) { 
   print "Enter the length: ";
   chomp ($length = <>);
   # checking for non-numeric characters
   unless ($length =~ /^[\d.]+$/){ 
      print "\nPlease enter a number\n";
      next;
   } 
   last if 0 <= $length and $length <= 99.99;
   print "It must be between 0 and 99.99\n";
}
[download]

There are other ways to attack this, but I have stayed fairly close to your logic. Hope this helps.

David

Update: coolmichael is right, of course. A revised regex might be: /^\d+(\.\d+)?$/

------------------------------------------------------------
"Perl is a mess and that's good because the
problem space is also a mess." - Larry Wall

For the most part, that will work but it will also match strings like 99.23.8427. I'm not sure if it will be a problem for the poster though, I just thought it important to point out.

Michael.