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Re: Filtering CGI Input

by crashtest (Curate)
on Apr 24, 2005 at 06:15 UTC ( #450882=note: print w/replies, xml ) Need Help??

in reply to Filtering CGI Input

My input should be any number from 0 to 99999.
Well, then why use regular expressions at all? Isn't this just a simple number comparison? How about:
if ($sid < 0 or $sid > 99_999){ ... }

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Re^2: Filtering CGI Input
by davidj (Priest) on Apr 24, 2005 at 07:10 UTC
    No, it is not that simple as the following code demonstrates:
    #!/usr/bin/perl use strict; my $num = "123abc"; print "valid\n" if $num > 0 && $num < 99999; exit;
    This will print 'valid', even though it does not meet the OP's criteria.

    Thus, if the value "123abc" is passed from a web form to a cgi script, the code you suggest will validate it. The reason for this is because when using numeric comparisons, Perl will treat any string that begins with a number as a number. This is clearly not what the OP wants.


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