PHP preg_match_all + str_replace

问题:

I need to find a way to replace all the <p> within all the <blockquote> before the <hr />.

Here's a sample html:

<p>2012/01/03</p>
<blockquote>
    <h4>File name</h4>
    <p>Good Game</p>
</blockquote>
<blockquote><p>Laurie Ipsumam</p></blockquote>
<h4>Some title</h4>
<hr />
<p>Lorem Ipsum</p>
<blockquote><p>Laurel Ipsucandescent</p></blockquote>

Here's what I got:

    $pieces = explode("<hr", $theHTML, 2);
    $blocks = preg_match_all('/<blockquote>(.*?)<\/blockquote>/s', $pieces[0], $blockmatch); 

    if ($blocks) { 
        $t1=$blockmatch[1];
        for ($j=0;$j<$blocks;$j++) {
            $paragraphs = preg_match_all('/<p>/', $t1[$j], $paragraphmatch);
            if ($paragraphs) {
                $t2=$paragraphmatch[0]; 
                for ($k=0;$k<$paragraphs;$k++) { 
                    $t1[$j]=str_replace($t2[$k],'<p class=\"whatever\">',$t1[$j]);
                }
            }
        } 
    } 

I think I'm really close, but I don't know how to put back together the html that I just pieced out and modified.

回答1:

You could try using simple_xml, or better DOMDocument (http://www.php.net/manual/en/class.domdocument.php) before you make it a valid html code, and use this functionality to find the nodes you are looking for, and replace them, for this you could try XPath (http://w3schools.com/xpath/xpath_syntax.asp).

Edit 1:

Take a look at the answer of this question:

RegEx match open tags except XHTML self-contained tags

回答2:

$string = explode('<hr', $string);
$string[0] = preg_replace('/<blockquote>(.*)<p>(.*)<\/p>(.*)<\/blockquote>/sU', '<blockquote>\1<p class="whatever">\2</p>\3</blockquote>', $string[0]);
$string = $string[0] . '<hr' . $string[1];

output:

<p>2012/01/03</p>
<blockquote>
    <h4>File name</h4>
    <p class="whatever">Good Game</p>
</blockquote>
<blockquote><p class="whatever">Laurie Ipsumam</p></blockquote>
<h4>Some title</h4>
<hr />
<p>Lorem Ipsum</p>
<blockquote><p>Laurel Ipsucandescent</p></blockquote>