替换php中字符串中标签之间的子字符串

Question

我已经为此工作了一整天，但找不到可以像我有字符串一样替换 php 中字符串中的子字符串的解决方案

'<div>
   <h2>this is <span>String</span> found in h2 tag</h2>
   <p>Hello World</p>
   <h2>this is <span>String</span> found in h2 tag</h2>
   <p>Hello Universe</p>
   <h2>this is <span>String</span> found in h2 tag</h2>
</div>'

我想获取 h2 中的每个字符串，然后执行一些 htmlentity 替换，例如

$str = 'this is <span>String</span> found in h2 tag';
$sanitized = htmlspecialchars($str,ENT_QUOTES);

然后输出完整的字符串但被替换。

如何实现？

<div>
    <h2>this is &lt;span&gt;String&lt;/span&gt; found in h2 tag</h2>
    <p><b>Hello</b> World</p>
    <h3>this is <span>String</span> found in h2 tag</h3>
    <p><b>hello</b> Universe</p>
    <h2>this is &lt;span&gt;String&lt;/span&gt; found in h2 tag</h2>
</div>

Answer 1

您可以使用preg_replace_callback()。匹配<h2>标签的正则表达式是：

/<h2>(.+?)<\/h2>/  

如果您想匹配所有 <hx>tags，请改用以下内容：

/<h([1-6])(.*?)<\/h\1>/ 

在回调函数中，您可以更改匹配的字符串。例如：

$html = <<< EOH

<div>
   <h2>this is <span>String</span> found in h2 tag</h2>
   <p>Hello World</p>
   <h2>this is <span>String</span> found in h2 tag</h2>
   <p>Hello Universe</p>
   <h2>this is <span>String</span> found in h2 tag</h2>
</div>

EOH;

$html = preg_replace_callback("/<h2>(.+?)<\/h2>/", function($matches) {
    /* Convert content of <h2> tags to HTML entities. */
    $altered =  htmlspecialchars($matches[1], ENT_QUOTES);

    /* Put the converted content back inside <h2> tag and return it. */
    return str_replace($matches[1], $altered, $matches[0]);
}, $html);

$html = preg_replace_callback("/<p>(.+?)<\/p>/", function($matches) {
    /* Make match bold. */
    $altered = "<b>" . $matches[1] . "</b>";

    /* Put the converted content back inside <p> tag and return it. */
    return str_replace($matches[1], $altered, $matches[0]);
}, $html);

print $html;

上述脚本的输出为：

<div>
   <h2>this is &lt;span&gt;String&lt;/span&gt; found in h2 tag</h2>
   <p><b>Hello World</b></p>
   <h2>this is &lt;span&gt;String&lt;/span&gt; found in h2 tag</h2>
   <p><b>Hello Universe</b></p>
   <h2>this is &lt;span&gt;String&lt;/span&gt; found in h2 tag</h2>
</div>