split input without function split

#!/usr/bin/env perl
use strict;
use warnings;
my @ar;
while (<>) {
  chomp;
  my ($i, $j) = (0, 0);
  for (; $i < length; ++$i) {
    my $s = substr $_, $i, 1;
    if ($s eq ' ' || $s eq '.' || $s eq ',') {
      push @ar, substr $_, $j, $i - $j;
      $j = $i + 1;
    }
  }
  if ($i != $j) {
    push @ar, substr $_, $j, $i - $j;
  }
}
print join ' ', @ar;
print "\n";