WordPress函数get_previous_post用于获取上一篇文章，可以限制返回相同分类的上一篇文章，需要用在文章页面模板里。
get_previous_post( boolean $in_same_cat, string $excluded_categories )函数参数
$in_same_cat
布尔值，默认值：false
如果为true，则输出与当前文章相同分类下的上一篇文章。
$excluded_categories
字符串值，默认为空
要排除的分类ID
函数返回值
函数返回值示例：
WP_Post Object (
[ID] => 2283
[post_author] => 1
[post_date] => 2019-09-13 21:39:48
[post_date_gmt] => 2019-09-13 13:39:48
[post_content] => 文章内容
[post_title] => 文章标题
[post_excerpt] =>文章摘要
[post_status] => publish
[comment_status] => open
[ping_status] => closed
[post_password] =>
[post_name] =>文章别名
[to_ping] =>
[pinged] =>
[post_modified] => 2019-09-13 21:39:48
[post_modified_gmt] => 2019-09-13 13:39:48
[post_content_filtered] =>
[post_parent] => 0
[guid] => https://www.zz2zz.com/?p=2283
[menu_order] => 0
[post_type] => post
[post_mime_type] =>
[comment_count] => 0
[filter] => raw
)函数使用示例
输出上一篇文章链接，这里链接地址没有直接使用guid的值，而是使用get_permalink()函数获取伪静态链接。
<?php
$prev_post = get_previous_post();
if (!empty( $prev_post )) {
echo '<a href="' . get_permalink($prev_post) . '">' . $prev_post->post_title . '</a>';
}
?>扩展阅读
get_previous_post()函数位于：wp-includes/link-template.php
