Regexp directives (like .) lose their special meaning inside character classes. You want
qr/^.{0,1000}$/s
or
qr/(?s:^.{0,1000}$)/

In character classes,

• A leading ^ will negate the character class.
• You can use Perl double-quote escapes (e.g. \x12, \cZ).
• $ and @ start variable interpolation (e.g. $var, @var, $var[4]).
• You can use Perl character classes (e.g. \d, \w, \s).
• You can use POSIX character classes (e.g. [:digit:], [:word:], [:space:])
• A dash can be used to create ranges (e.g. a-z).
• A slash (\) will cause the next character to be interpreted literally.
• Any other character (including ., * and +) will be matched literally.

Update: Added list.

The regex question has been answered by ikegami and graff, but I just thought I'd toss this into the mix.

If all you want to do is "match" (validate) that a string has between zero and 1000 characters, you could also do this:

if( defined( $string ) and length( $string ) <= 1000 ) {
    print "It's a match!\n";
}
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Because with the "s" modifier at the end of the regex, the wildcard "." (not within square brackets) will match anything including newlines.

As explained in the first reply, when you put "." inside square brackets as part of a character class, it loses its status as a wildcard, and will only match a literal period. If you wanted to insist on using a square-bracketed character class to match between 0 and 1000 characters, any of the following would work, but all of them would seem pretty goofy looking compared to the simpler version that simply uses "." as a wildcard with the "s" modifier.

# alternatives to  qr/^.{0,1000}$/s :

qr/^[\s\S]{0,1000}/;
qr/^[\d\D]{0,1000}/;
qr/^[\w\W]{0,1000}/;
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