sub isvaliddate {
my $input = shift;
if ($input =~ m!^((?:19|20)\d\d)[- /.](0[1-9]|1[012])[- /.](0[1-9]|[12][0-9]|3[01])$!) {
# At this point, $1 holds the year, $2 the month and $3 the day of the date entered
if ($3 == 31 and ($2 == 4 or $2 == 6 or $2 == 9 or $2 == 11)) {
return 0; # 31st of a month with 30 days
} elsif ($3 >= 30 and $2 == 2) {
return 0; # February 30th or 31st
} elsif ($2 == 2 and $3 == 29 and not ($1 % 4 == 0 and ($1 % 100 <> 0 or $1 % 400 == 0))) {
return 0; # February 29th outside a leap year
} else {
return 1; # Valid date
}
} else {
return 0; # Not a date
}
}
This is an excerpt from another community work.
