Custom Post Except lengths

<?php
/*Add this block to functions.php */
function my_excerpt_length() {
global $myExcerptLength;

if ($myExcerptLength) {
    return $myExcerptLength;
} else {
    return 80; //default value
    }
}
add_filter('excerpt_length', 'my_excerpt_length');
?>


<?php
/*Add this in your theme where you want the excerpt to show*/
$myExcerptLength=35;
   echo get_the_excerpt();
   $myExcerptLength=0;
?>