我有这个功能：

function wpse_210493_apply_advertising_position( &$posts, $return = false ) {
    $ad_posts = array();

    $content_posts = array_filter(
        $posts,
        function ( $post ) {
            $position = get_post_meta( $post->ID, \'rw_adversiting_position\', true );

            if ( empty( $position ) ) {
                return true;
            }

            $ad_posts[ intval( $position ) ] = $post;

            return false;
        } );

    $content_posts = array_values( $content_posts );

    ksort( $ad_posts );

    echo "sdfksfkjshdfsdf";

    foreach ( $ad_posts as $position => $ad ) {
        array_splice( $content_posts, $position, 0, $ad );
    }

    if ( $return ) {
        return $content_posts;
    } else {
        $posts = $content_posts;
    }
}

我需要调试$ad_posts 在ksort() 但输出不会发送到浏览器。我用echo 您看到了，并且该文本也不会作为输出发送到浏览器。如何正确调试这些值？

?><pre><?php var_dump( $variable_to_test ); ?></pre><?php

?><pre><?php var_dump($ad_posts); ?></pre><?php 

error_log(your-variable-or-whatever);

error_log( \'MY STUFF: \' . print_r( $something, true ) );