You can get the current year using localtime, and then compare it to the form field.
Before comparing, though, you should check that the year field is numeric.
my $yearfield = get_it_from_somewhere();
my $current_year = (localtime)[5] + 1900;
die "invalid number\n" unless $yearfield =~ /^\d+$/;
die "invalid year\n" if $yearfield > $current_year;

[download]
See the localtime page for more details.

HTH
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In reply to Re: How to validate the year of a date? by gmax
in thread How to validate the year of a date? by slok

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