for( $i = 0; $i <= $#link; $i++ ) {
...

##</code><code>##

for my $i ( 0 .. $#link )
{
...

##</code><code>##

for my $i ( 0 .. $#{ $link_ref } )
{
    my $links = $link_ref->[ $i ]->[ 0 ];
}