post_class output in wrong area?

Question

Trying this in my functions file. There is actually a lot more to this function than I am showing, but this is the important part that is messed up.

function xyz_loop() {
        $defaults = array (
            'before' => 'article id="post-' .get_the_ID(). '"' .post_class('clearfix'). 'role="main">',
            'after' => '/article>',
        );


    $args = wp_parse_args( $args, $defaults );
    extract( $args, EXTR_SKIP );

    echo $before;

    echo 'doing stuff here';

    echo $after;}

the problem is the post_class is outputting the post classes before the article container instead of inside it.

Can I not use post_class like this?

Answer 1

post_class() echos so that's you're problem.

From the codex:

If you would prefer to have the post classes returned instead of echoed, you would want to use get_post_class().

So just do this:

$the_post_classes = get_post_class( 'clearfix' );
$the_post_class_string = '';
foreach( $the_post_classes as $post_class ) {
    $the_post_class_string .= $post_class . ' ';
}

$defaults = array (
    'before' => 'article id="post-' .get_the_ID(). '"' .$the_post_class_string. 'role="main">',
    // etc...

UPDATE: Sorry. I forgot this returns an array and not a string. You just need to iterate through the results before spitting them out. Code above is updated and tested.