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

my $x="hello world"; # 11 chars
while ( $x =~ /(.)(.)?/g ) {
    my ( $y, $z ) = ( $1, $2 );
    $z = "" unless $z; # prevents the warning
                       # "use of uninitialized ..." 
    print"<$y:$z>\n";
}
__END__
<h:e>
<l:l>
<o: >
<w:o>
<r:l>
<d:>