On Tue, May 11, 2004 at 05:28:13PM -0600, Jacob Fugal wrote:
> QuickBrownFox wrote:
> >Hey everybody,
> >
> >I'm using a regular expression for validation here at work that I wanted
> >some advice on. Specifically, it checks to see if the time is formatted
> >correctly in the 12-hour format (hh:mm:ss (AM|PM)). So far, this is
> >what I've got:
> >
> >/^(0?[1-9]|1[0-2]):([0-5][0-9]):9[0-5][0-9]) (AM|PM)$/
> ^
> Looks fine, except I think you missed a shift key (above the marker, if
> that 9 is a (, then everything's fine). Although I'd relax the
> requirement for seconds and allow variable whitespace:
>
> /^(0?[1-9]|1[0-2]):([0-5][0-9])(:([0-5][0-9]))?\s*(AM|PM)$/
I'd also compress the AM|PM -> ([AP]M) ... slightly more efficient.
I'd also separate out the check to programming logic. Regexes can get hairy
when you try to do a lot in them. Especially in languages that arent' really
built around regexes.
> sub check_time
> {
> # get input and check general format
>
> my $time = shift;
> if ($time =~
> /^(0?[1-9]|1[0-2]):([0-5][0-9])(:([0-5][0-9]))?\s*(AM|PM)$/)
> {
> # get parts and convert to 24 hours string w/o colons (default
> # seconds to 0
>
> my ($hour, $min, $sec, $am_or_pm) = ($1, $2, $4, $5);
> $hour += 12 if $am_or_pm eq 'PM';
> $sec = 0 unless $sec;
> my $new_time = $hour . $min . $sec;
>
> # make sure the time is between 8AM and 5PM (inclusive)
>
> return ($new_time ge '080000' and $new_time le '170000');
> }
> else { return 0; }
> }
<WARNING: Perl Hacker At Work>
If you're gonna do it that way, I'd change it to something like:
use Time::ParseDate; # Included in the default installation.
sub check_time {
my ( $time, $start, $end ) = @_;
my $s = parsedate( $start || '00:00:00' ) or return undef;
my $e = parsedate( $end || '23:59:59' ) or return undef;
my $t = parsedate( $time ) or return undef;
return undef unless $s <= $t && $t <= $e;
my @t = ( localtime( $t ) )[2,1,0];
my $t[3] = $t[0] > 12 ?
do { $t[0] -= 12 ; "PM" } :
do { $t[0] = 12 if $t[0] == 0 ; "AM" };
sprintf "%2d:%2d:%2d %s", @t;
}
That was fun. Hmmm ... maybe a local Fun With Scripting Languages mailing
list (as opposed to Fun With Perl).
Alan
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