How can I print N array elements with delimiters per line? - perl

Question

I have an array in Perl I want to print with space delimiters between each element, except every 10th element which should be newline delimited. There aren't any spaces in the elements if that matters.
I've written a function to do it with for and a counter, but I wondered if there's a better/shorter/canonical Perl way, perhaps a special join syntax or similar.
My function to illustrate:
sub PrintArrayWithNewlines
{
my $counter = 0;
my $newlineIndex = shift #_;
foreach my $item (#_)
{
++$counter;
print "$item";
if($counter == $newlineIndex)
{
$counter = 0;
print "\n";
}
else
{
print " ";
}
}
}

Answer 1

I like splice for a job like this:
sub PrintArrayWithNewlines {
my $n = 10;
my $delim = " ";
while (my #x = splice #_, 0, $n) {
print join($delim, #x), "\n";
}
}

Answer 2

You can use List::MoreUtils::natatime:
use warnings; use strict;
use List::MoreUtils qw( natatime );
my #x = (1 .. 35);
my $it = natatime 10, #x;
while ( my #v = $it->() ) {
print "#v\n"
}
Output:
C:\Temp> x
1 2 3 4 5 6 7 8 9 10
11 12 13 14 15 16 17 18 19 20
21 22 23 24 25 26 27 28 29 30
31 32 33 34 35

Answer 3

If you do not want to use any external modules, you can use array slices:
use warnings; use strict;
my #x = (1 .. 95);
my $n = 10;
for my $i ( 0 .. int #x/$n ) {
no warnings 'uninitialized';
print "#x[$n * $i .. $n * ($i + 1) - 1]\n";
}

Answer 4

The functions by and every in my module List::Gen can solve this problem:
use List::Gen;
for (every 10 => 'a' .. 'z') {
print "#$_\n"
}
# a b c d e f g h i j
# k l m n o p q r s t
# u v w x y z
it can also be written
foreach (by 10 => 'a' .. 'z') {
print "#$_\n"
}
or using the functional form:
mapn {print "#_\n"} 10 => 'a' .. 'z'; # #_ not #$_ here
or an iterator if that's your style:
my $letters = by 10 => 'a' .. 'z';
while (my $line = $letters->next) {
print "#$line\n";
}

Answer 5

You can also use map with a modification to PrintArrayWithNewlines:
#!/usr/bin/perl -w
use strict;
sub PrintArrayWithNewlines
{
my #array = #_;
my $newlineIndex = 10;
foreach my $item (#array) {
++$globalCounter;
print "$item";
if ($globalCounter == $newlineIndex) {
$globalCounter = 0;
print "\n";
}
else {
print " ";
}
}
}
my $globalCounter = 0;
my #myArray = 'a' .. 'z'
map { PrintArrayWithNewlines($_) } #myArray;
print "\n";
The output would be:
$ ./test.pl
a b c d e f g h i j
k l m n o p q r s t
u v x y z