#!/usr/bin/perl -w
use strict;

sub fixedsplit {
    my ($data,$len) = @_;
    ($data =~ /(.{1,$len})/g);
}

my $data = "abcdefghijklmnopqrstuvwxyz";
my @fields;

@fields = fixedsplit($data,4);
print "@fields\n";
@fields = fixedsplit($data,6);
print "@fields\n";
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Produces:

abcd efgh ijkl mnop qrst uvwx yz
abcdef ghijkl mnopqr stuvwx yz
[download]

---
print map { my ($m)=1<<hex($_)&11?' ':'';
$m.=substr('AHJPacehklnorstu',hex($_),1) }
split //,'2fde0abe76c36c914586c';
[download]