FAQ 4.12 How do I find the day or week of the year?

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4.12: How do I find the day or week of the year?

The "localtime" function returns the day of the year. Without an
argument "localtime" uses the current time.

my $day_of_year = (localtime)[7];

The "POSIX" module can also format a date as the day of the year or week
of the year.

use POSIX qw/strftime/;
my $day_of_year = strftime "%j", localtime;
my $week_of_year = strftime "%W", localtime;

To get the day of year for any date, use "POSIX"'s "mktime" to get a
time in epoch seconds for the argument to "localtime".

use POSIX qw/mktime strftime/;
my $week_of_year = strftime "%W",
localtime( mktime( 0, 0, 0, 18, 11, 87 ) );

You can also use "Time::Piece", which comes with Perl and provides a
"localtime" that returns an object:

use Time::Piece;
my $day_of_year = localtime->yday;
my $week_of_year = localtime->week;

The "Date::Calc" module provides two functions to calculate these too:.

use Date::Calc;
my $day_of_year = Day_of_Year( 1987, 12, 18 );
my $week_of_year = Week_of_Year( 1987, 12, 18 );


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