Re: Print every past three months from current month

[wazat]

Why not take a slice instead of using splice.

my @a = qw( a b c d e f g );
sub f {
    my $i = shift;  
    print join(',',  @a[$i-2, $i-1, $i]), "\n";
}

f(0);
f(1);
f(2);
f(6);

outputs

f,g,a
g,a,b
a,b,c
e,f,g

[Anonymous Monk]

Hi, think if it was months, the count has to go backwards, and I can't get it to do it:


my @months = qw( January February March April May June July October No
+vember December );

# passing 4 for April, I should get "February March April", instead I 
+get: "March April May".

f(4);
sub f {
    my $i = shift;  
    print join(',',  @months[$i-2, $i-1, $i]), "\n";
}


Thanks!

[wazat]

Remember that perl array indices start at zero. April would have index 3, not 4. Also you are missing August and September.

my @months = qw( January February March April May June July August Sep
+tember October November December );

f(3); # Apr
f(0); # Jan
f(11); # Dec

sub f {
    my $i = shift;  
    print join(',',  @months[$i-2, $i-1, $i]), "\n";
}

Output

February,March,April
November,December,January
October,November,December

[AnomalousMonk]

c:\@Work\Perl\monks>perl -wMstrict -le
"my %months_name = qw(
    1 January     2 February  3 March      4 April
    5 May         6 June      7 July       8 August
    9 September  10 October  11 November  12 December
    );
 ;;
 my @months = map $months_name{$_}, sort { $a <=> $b } keys %months_na
+me;
 ;;
 for my $n (1 .. 12) {
   my @prev_3 = map $n-1+$_, -3 .. -1;
   @prev_3 = @months[ @prev_3 ];
   print qq{(@prev_3) before $months_name{$n} (month $n)};
   }
"
(October November December) before January (month 1)
(November December January) before February (month 2)
(December January February) before March (month 3)
(January February March) before April (month 4)
(February March April) before May (month 5)
(March April May) before June (month 6)
(April May June) before July (month 7)
(May June July) before August (month 8)
(June July August) before September (month 9)
(July August September) before October (month 10)
(August September October) before November (month 11)
(September October November) before December (month 12)