How do you add (,) separator on custom post type category

Hello guys,

I need your help again..
How do you add (,) separator on custom post type category, here is my code:

$terms = get_the_terms(  get_the_ID(), 'portfolio_categories' );
foreach ($terms as $term) { 
      echo '<a href="'.get_term_link($term->slug, 'portfolio_categories').'">'.$term->name.'</a>';
}

I read the get_term_link codex but can find solution their..

thanks,
mark

rifki said
http://codex.wordpress.org/Function_Reference/get_the_term_list

thank you very much rifki…