Examples for WP filter

wp_filter.php

<?php
/*
Plugin Name: Filter the content to remove ADULTKEYWORD. This is an example plugin
*/

add_filter('the_content', 'fm_filter_the_main_loop', 1);

function fm_filter_the_main_loop($content)
{

    // Check if we're inside the main loop in a single Post.
    if (is_singular() && in_the_loop() && is_main_query()) {
        $content = str_replace('ADULTKEYWORD', '...', $content);
    }

    return $content;
}

add_filter('the_title', 'fm_format_title', 1);

function fm_format_title($title)
{
    if (is_singular() || is_front_page()) {
        $title = $title." - by ". get_the_author();
    }

    return $title;
}