wordpress中的<!--more-->截取输出摘要怎么判断?

wordpress的代码

function get_extended($post) {
    //Match the new style more links
    if ( preg_match('/<!--more(.*?)?-->/', $post, $matches) ) {
        list($main, $extended) = explode($matches[0], $post, 2);
        $more_text = $matches[1];
    } else {
        $main = $post;
        $extended = '';
        $more_text = '';
    }

    // Strip leading and trailing whitespace
    $main = preg_replace('/^[\s]*(.*)[\s]*$/', '\\1', $main);
    $extended = preg_replace('/^[\s]*(.*)[\s]*$/', '\\1', $extended);
    $more_text = preg_replace('/^[\s]*(.*)[\s]*$/', '\\1', $more_text);

    return array( 'main' => $main, 'extended' => $extended, 'more_text' => $more_text );
}

javascript版本

'正文内容<!--more-->截断更多内容'.split('<!--more-->')[0];

返回 '正文内容'

php

`$errrr=explode('','正文内容截断更多内容');
echo $errrr[0]`

输出 '正文内容'