Adding Custom Class to the_content

custom_the_content.php

<?php

//Adding custom class to posts is easy with the post_class filter

add_filter('post_class', 'custom_content_class');

function custom_content_class($classes) {
	$classes[] = 'custom_class';
	return $classes;
}

//Same with adding custom classes to the body of ALL pages/posts

add_filter('body_class', 'custom_content_class');

function custom_content_class($classes) {
	$classes = 'custom_class';
	return $classes;
}

// But this is not possible with the_content
// The best that I've come up with so far is adding a wrapper
// div inside of the_contentlike so:

add_filter('the_content', 'custom_content_class');

function custom_content_class($content) {
    $mcil_class = '<div class="custom_class">';
    $mcil_class .= $content;
    $mcil_class .= '</div>';

    $filteredcontent = $mcil_class;

    return $filteredcontent;
}