potential date and time issues / code cleanup

[Conal]

Hi can anyone kindly help me out with making this code more robust and useful.. for the purposes of the data i am working with days start at 5pm and finish at 4.59pm the next day. i have a data file for each day containing my readings

i am not very good at this so please point out any others areas i might be messing up or could do better if you feel so inclined

use File::Copy;
use Time::Local;

my ($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdist) = localtime 
+time;

my $week="daily/Sun-23-Mar-2008/";

.... other code 

#########   daily file creation ########
########################
#create new file for new day @ 1700

if ($hour == 17 && $min ==0 && min !=30)

       { qx(touch $week.$mday); }


#####################
### calculate REAL day
### by subtracting 1 from mday if hour > 00 and < 1700
###  WHATABOUT THE MONTH???

my $filemday = $mday;

if ($hour < 17 && $hour >= 0)

    { $filemday = $filemday-1; }
my $dayfile = $week.$filemday.".txt";


### print data to file

if (-e $dayfile) { 
        open (DATA,">>$dayfile");
        print DATA ""$hour:$min,some data\n";
        close (DATA);
        }

... other code

now obviously subtracting 1 from the $mday variable is gonna leave me in a whole load crap. Can anyone suggest any ideas for what i can do to fix this please?

thanks.

[ikegami]

Getting the previous day's date is a FAQ. You should find a variety of answers on PM. One way is the following:

# Jan = 1
my ($yest_y, $yest_m, $yest_d) = (
   gmtime(
      timegm(0,0,0,$today_d,$today_m-1,$today_y) - 24*60*60
   )
)[5,4,3];
$yest_m += 1;
$yest_y += 1900;

Use timegm + gmtime even for local dates.

[walto]

I like Date::Manip to handle date and time issues (Date::Manip).

I am not sure if this is intentional but
if ($hour == 17 && $min ==0 && min !=30)

min !=30 could be a typo for $min !=30
but is $min !=30 not always true if $min ==0 ?

[Conal]

ha .. good spot walto .. thankyou! guess that relatively minor issue infers most of the other code is pretty ok.. heh .. ? ;p

thanks to everyones reply ..i have a few ideas now for when i go back at my code.

[nefigah]

There's the Date::Calc CPAN module:

use warnings;
use strict;
use Date::Calc::Object;

my $date = Date::Calc->today - 1;

Which will get you yesterday's date in a pretty clean way.

[wade]

First of all, don't forget the:

use strict;
use warnings;

If you're going to do much with dates, you should check out Date::Simple or, for more complicated stuff DateTime over on CPAN. They've worked out all the details so that you can use your creative juices on newer, more interesting problems.

[CountZero]

if ($hour == 17 && $min ==0 ...

Unless your program is running continuously (which seems a waste of processorcycles) , you only have a one minute window in which this test will be triggered, so you should be pretty sure that indeed you do not miss this window.

On the other hand if your program does run continuously, you have to test whether your file exists already or you will be overwriting it several times within the window.