記事ページ（single.php）で、次の記事（前の記事）のコメント数を取得（表

ポストの順序は、pevious_post_link(), next_post_link() と同じです。

★functions.php

function previous_comments_num()
{
	$args = array(
		'post_type'        => 'post',
		'orderby'          => 'post_date',
		'order'            => 'ASC',
		'numberposts'      => 1,
		'suppress_filters' => false
	);
	add_filter( 'posts_where', 'previous_comments_num_where');
	$previous_post = get_posts($args);
	remove_filter( 'posts_where', 'previous_comments_num_where' );
	if(!empty($previous_post)) {
		$num = get_comments_number($previous_post[0]->ID);
	} else {
		$num = -1;
	}
	return $num;
}

function next_comments_num()
{
	$args = array(
		'post_type'        => 'post',
		'orderby'          => 'post_date',
		'order'            => 'DESC',
		'numberposts'      => 1,
		'suppress_filters' => false
	);
	add_filter( 'posts_where', 'next_comments_num_where');
	$next_post = get_posts($args);
	remove_filter( 'posts_where', 'next_comments_num_where' );
	if(!empty($next_post)) {
		$num = get_comments_number($next_post[0]->ID);
	} else {
		$num = -1;
	}
	return $num;
}

function previous_comments_num_where( $where = '' ) {
    global $post;
    $where .= " AND post_date > '" . $post->post_date . "'";
    return $where;
}

function next_comments_num_where( $where = '' ) {
    global $post;
    $where .= " AND post_date < '" . $post->post_date . "'";
    return $where;
}

★single.php

<?php
$prev_num = previous_comments_num();
if ($prev_num != -1) echo "$prev_num<br />";
$next_num = next_comments_num();
if ($next_num != -1) echo $next_num;
?>