如何使用PHP提取HTML输入标记的值

$html =<input type="text" name="username" value="JohnDoe">';
$pattern = '/value="(.*?)"/';
preg_match($pattern, $html, $matches);
$value = $matches[1];
echo $value; // 输出：JohnDoe

$html =<input type="text" name="username" value="JohnDoe">';
$doc = new DOMDocument();
libxml_use_internal_errors(true);
$doc->loadHTML($html);
$inputs = $doc->getElementsByTagName('input');
foreach ($inputs as $input) {
    if ($input->getAttribute('name') == 'username') {
        $value = $input->getAttribute('value');
        echo $value; // 输出：JohnDoe
    }
}

require_once('simple_html_dom.php');
$html =<input type="text" name="username" value="JohnDoe">';
$dom = str_get_html($html);
$input = $dom->find('input[name=username]', 0);
$value = $input->value;
echo $value; // 输出：JohnDoe