<?php
//odd and even loop
function oddeven_post_class ( $classes ) {
   global $current_class;
   $classes[] = $current_class;
   $current_class = ($current_class == 'odd') ? 'even' : 'odd';
   return $classes;
}
add_filter ( 'post_class' , 'oddeven_post_class' );
global $current_class;
$current_class = 'odd';
?>