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FAQ 4.47 How do I handle circular lists?

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4.47: How do I handle circular lists?

(contributed by brian d foy)

If you want to cycle through an array endlessly, you can increment the
index modulo the number of elements in the array:

my @array = qw( a b c );
my $i = 0;

while( 1 ) {
print $array[ $i++ % @array ], "\n";
last if $i > 20;

You can also use "Tie::Cycle" to use a scalar that always has the next
element of the circular array:

use Tie::Cycle;

tie my $cycle, 'Tie::Cycle', [ qw( FFFFFF 000000 FFFF00 ) ];

print $cycle; # FFFFFF
print $cycle; # 000000
print $cycle; # FFFF00

The "Array::Iterator::Circular" creates an iterator object for circular

use Array::Iterator::Circular;

my $color_iterator = Array::Iterator::Circular->new(
qw(red green blue orange)

foreach ( 1 .. 20 ) {
print $color_iterator->next, "\n";


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