in reply to How to iterate thru entire array with start point other than beginning

#!/usr/bin/perl -l

# http://perlmonks.org/?node_id=1170987

use strict;
use warnings;

my @month_name = qw(January February March April May June July August 
+September October November December);

for my $start (0 .. 11)
  {
  my @wanted = (@month_name, @month_name)[$start .. $start + 11];
  print "@wanted";
  }

[download]
  • Comment on Re: How to iterate thru entire array with start point other than beginning
  • Download Code

Replies are listed 'Best First'.
Re^2: How to iterate thru entire array with start point other than beginning
by dirtdog (Monk) on Sep 01, 2016 at 18:21 UTC

    I spoke too soon. I'm actually a little stumped on the % modulo operator and the example. I see a lot more than 12 months being printed out. The goal is to start with current month +1 (so October if using today in the example) and then print the 12 months in order from there.. 

    
#!/usr/bin/perl
use POSIX 'strftime';

use strict;

my ($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst) = localtime;
my $curr_mth = sprintf "%2d", strftime('%m', $sec,$min,$hour,$mday,$mo
+n,$year,$wday,$yday,$isdst);

my @month_name = qw(January February March April May June July August 
+September October November December);

        for my $m ( 0 .. $#month_name) {
                print "Month name is: $month_name[$m]\n";
        }

    [download]

    I'm trying to get out as follows:

    Month name is: October
Month name is: November
Month name is: December
Month name is: January
Month name is: February
Month name is: March
Month name is: April
Month name is: May
Month name is: June
Month name is: July
Month name is: August
Month name is: September

    [download]

    then next month the output would be:

    Month name is: November
Month name is: December
Month name is: January
Month name is: February
Month name is: March
Month name is: April
Month name is: May
Month name is: June
Month name is: July
Month name is: August
Month name is: September
Month name is: October

    [download]
[reply]
[d/l]
[select]

      If you want to use the % operator, it can be quite simple. To expand on the GP anonymonk's script:

      #!/usr/bin/env perl 
use strict;
use warnings;

# Set an array of names
my @names = qw/January February March April May June
    July August September October November December/;
# Find the index number of next month
my $next = (localtime)[4] + 1;

# Loop over the next 12 months and print the month names in sequence
for my $monpos ($next .. $next + 11) {
    print "Month is $names[$monpos % 12]\n";
}

      [download]

      Please ask if anything in this piece of code is unclear.

[reply]
[d/l]

        Thanks Hippo. It does seem simple now that I understand it!

[reply]

      I have some code that works, but boy o' boy is it ugly.

      #!/usr/bin/perl
use POSIX 'strftime';

use strict;

my $m;

my ($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst) = localtime;
my $curr_mth = sprintf "%2d", strftime('%m', $sec,$min,$hour,$mday,$mo
+n,$year,$wday,$yday,$isdst);

my @month_name = qw(January February March April May June July August 
+September October November December);

        for  ( $curr_mth .. $#month_name) {
                print "Month name is: $month_name[$_]\n";
                $m++;
        }

        if ( $m < 12 ) {
                for my $n ( 0 .. ($#month_name - $m) ) {
                        print "Month name is: $month_name[$n]\n";
                }
        }

      [download]
[reply]
[d/l]
        but boy o' boy is it ugly

        I always say, first make it work. THEN make it pretty. ;-)

        HTH,

        planetscape
[reply]

In Section Seekers of Perl Wisdom