How to truncate characters in product description with WooCommerce - php

Question

I have found out how to add a short description to the thumbnails for products in WooCommerce, but how do I truncate them to a certain length, say 30 characters.
All the answers to do with editing the functions.php file dont mention where in the file to put the code.
My code in my functions.php file is:
add_action('woocommerce_after_shop_loop_item_title','add_title_description',9);
function add_title_description(){
echo get_post_meta($product->id, 'title-description', true)? '<span class="title-description">' . get_post_meta($product->id, 'title-description', true) . '</span><br />' : '';
}

Answer 1

use substr()
add_action('woocommerce_after_shop_loop_item_title','add_title_description',9);
function add_title_description()
{
$titleDescription = get_post_meta($product->id, 'title-description', true);
if( !empty($titleDescription) )
{
if( strlen($titleDescription) > 30 )
$titleDescription = substr($titleDescription, 30);
printf('<span class="title-description">%s</span><br />', $titleDescription);
}
}

Answer 2

My implementation grabbing the first 2 sentences instead of a character count.
/**
* Echo Truncated String
*
* #param string $string
* #return string
*/
function add_title_description( $titleDescription ) {
global $product;
$titleDescription = get_post_meta( $product->id, 'title-description', true );
// combine first 2 sentences
$sentence = preg_split( '/(\.|!|\?)\s/', $titleDescription, 3, PREG_SPLIT_DELIM_CAPTURE );
echo $titleDescription ? '<span class="title-description">' . $sentence[0] . $sentence[3] . '</span><br />' : '';
}
add_action( 'woocommerce_after_shop_loop_item_title', 'add_title_description', 4, 1 );

Answer 3

I added this:
function wcs_excerpt_length( $length ) {
return 15;
}
add_filter( 'product_description_length', 'wcs_excerpt_length' );