如何限制存档产品.php WordPress$category>描述中的摘录长度？

我想在echo '<p>' . $category->description . '</p>';中限制摘录长度为30个字符，这里是我的代码：

<?php
$orderby = 'name';
$order = 'asc';
$hide_empty = true ;
$cat_args = array(
'orderby'    => $orderby,
'order'      => $order,
'hide_empty' => $hide_empty,
);
$product_categories = get_terms( 'product_category', $cat_args );
if( !empty($product_categories) ){
echo '<div class="container">';
echo '<div class="row">';
foreach ($product_categories as $key => $category) {
echo '<div class="col-lg-6">';
echo '<div class="card">';
echo '<a href="'.get_term_link($category).'" >';
$image = get_field('product_category', $category );
if($image) {
echo '<img class="card-img-top" src="' . $image['url'] . '" alt="' . $image['alt'] .'">';
} else {
echo '<img class="card-img-top" src="/wp-content/uploads/2018/07/placeholder.png">';
}
echo '<h3>' . $category->name . '</h3>';
//echo $category->name;
echo '<p>' . $category->description . '</p>';
echo '<button class="button btn_medium btn_orange btn_squared btn_normal_style" href="'.get_term_link($category).'" >Discover more</button>';
echo '</a>';
echo '</div>';
echo '</div>';
}
echo '</div>';
echo '</div>';
}
else {
// no posts found
echo wpautop( 'Sorry, no products were found' );
}
?>

如何在echo '<p>' . $category->description . '</p>';中添加限制摘录长度？

谢谢，

肖恩。