Find week of a year given the date in mm/dd/yyyy

Question

I am trying to find the week that a date falls in, in a certain year. I have a bunch of files that need to be sorted into folders like "week1-2012" and "week34-2011". I tried searching but a lot of the results aren't really helping because I am currently using perl v5.6.1, super old and I can't download any modules. I also found this link ( How do I calculate the week number given a date?) of interest but was wondering how I would go about getting the day of year and week easily. Was thinking of getting the month, and adding the appropriate amount of days to find out the day in the year. Any help would be appreciated. An example of the year format I am looking for is

//year 2012
S  M  T  W  R  F  S
            1  2  3    <-- week #1 
4  5  6  7  8  9 10    <-- week #2 //came from the link

//dec year 2011
S   M  T  W  T  F  S
27 28 29 31            <-- week #52 or 53, not to sure the actual week

Answer 1

You can use core modules: POSIX and Time::Local

1.parse your date to (sec, min, hour, mday, month, year)

2.convert your date to seconds (epoch)

3.use function strftime to get week from current date

use strict;
use Time::Local;
use POSIX qw(strftime);

my $date = '08/15/2012';
my ($month, $day, $year) = split '/', $date;

my $epoch = timelocal( 0, 0, 0, $day, $month - 1, $year - 1900 );
my $week  = strftime( "%U", localtime( $epoch ) );

printf "Date: %s № Week: %s\n", $date, $week;

OUTPUT

Date: 08/15/2012 № Week: 33