Your regexp is matching anything that has the literal string "0-9" in it. And then the !~ negates that match. Thus, since anything you've tried probably does not include the literal string "0-9" somewhere in it, the full expression is always true.

You want to match a character class - e.g., \d matches all digits, thus using /\d/ is a bit closer. What this does is match any digit, anywhere in the string.

You actually want to match 1 to 5 digits. So you can use the {} modifier: /\d{1,5}/. This matches anywhere from 1 to 5 digits, anywhere in the string. But that still matches "a1b" since it has somewhere between 1 and 5 digits. So you want to anchor the match to both the beginning and the end. And thus we get /^\d{1,5}$/.

Hope that helps. perlretut may help.

I want to modify this filter so that it will accept lat/longs (-88.88888) that is 9 characters long and can include 0-9 and - and .

So does this look right?

~/^\d|\c(.|-)$/

All that I really want to do is make sure no other characters get in there except digits (0 thru 9) and the "." and "-" characters.

9 characters long? Does 1.3456789 count? Or do you really mean 5 digits after the decimal place only? I'm assuming the latter. And that the - sign doesn't count.

  /^-?(\d{1,3}(?:\.\d{1,5})?)$/
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That is, an optional leading - sign, followed by 1 to 3 digits (to allow for 180 degrees East/West), followed, optionally, by a dot, and then 1 to 5 more digits.

Better yet, try:

  use Regexp::Common;
  /^$RE{num}{decimal}{-places=>'0,5'}$/ and $_ <= 180;
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No sense reinventing the wheel. :-)

Both CGI::Untaint and Data::FormValidator provide an already-tested mechanism to do what you're attempting. They also both allow you to integrate your own patterns.

Overkill for a simple situation? I think not - as your application grows (and it will) would you prefer a scalable solution that you can get advice about from other users or a bunch of special-case regexes in your code?

Several things are wrong. /0-9/ will match '0-9' (exactly). And since it's a negated match, basically you are accepting all input unless it contains the literal text '0-9'.

You need a character class.

if( $sid =~ /^[^0-9]$/ ) {
    # exit here......
}
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The above code states if there are any characters in the string that are not numbers 0 through 9, exit.

It might actually be better to do it this way though:

if( $sid !~ m/^([0-9]{1,5})$/ ) {
    # exit
} else {
    $input = $1;
}
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...or better yet...

if( $sid =~ m/^([0-9]{1,5})$/ ) {
    $input = $1;
} else {
    # exit
}
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I think negated matches ( the !~ operator ) are usually just a way of adding confusion, and should be avoided unless absolutely necessary.

My input should be any number from 0 to 99999.

if ($sid < 0 or $sid > 99_999){
   ...
}
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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;
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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.

davidj