Евгений

<?php
$str = explode(' ','note book');
echo $str[0].'<b>'.$str[1].'</b>';
?>

$t = get_userdata(get_current_user_id());
echo $t != 0 ? 'user registered: '.date("d.m.Y",strtotime($t->user_registered)) : 'user not logged in';

if (is_admin())
{
    $query = new WP_Query(array(
        'category_name' => 'cat',
        'posts_per_page' => -1,
    ));

    if ($query->have_posts()) {
        while ($query->have_posts()) {
            $query->the_post();
            if (!get_post_meta(get_the_ID(), 'clicks', true)) update_post_meta(get_the_ID(), 'clicks', 0);
        }
    }
    wp_reset_postdata();
}