php - 使用 cURL 获取 HTTP header 并保存到变量

Question

我正在使用它来获取 XML 提要和 HTTP header

// Initiate the curl session
$ch = curl_init();

// Set the URL
curl_setopt($ch, CURLOPT_URL, $url);

// Allow the headers
curl_setopt($ch, CURLOPT_HEADER, true);

// Return the output instead of displaying it directly
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);

// Execute the curl session
$output = curl_exec($ch);

// Close the curl session
curl_close($ch);

// Cache feed
file_put_contents($filename, $output);

// XML to object
$output = simplexml_load_string($output);

// Return the output as an array
return $output;

它返回这些标题

HTTP/1.1 200 OK
Cache-Control: public, max-age=30
Content-Length: 5678
Content-Type: text/xml
Expires: Tue, 22 Nov 2011 15:12:16 GMT
Last-Modified: Tue, 22 Nov 2011 15:11:46 GMT
Vary: *
Server: Microsoft-IIS/7.0
Set-Cookie: ASP.NET_SessionId=1pfijrmsqndn5ws3124csmhe; path=/; HttpOnly
Data-Last-Updated: 11/22/2011 15:11:45
X-AspNet-Version: 4.0.30319
X-Powered-By: ASP.NET
Date: Tue, 22 Nov 2011 15:11:46 GMT

我只希望它返回 HTTP header 的一部分，即

Expires: Tue, 22 Nov 2011 15:12:16 GMT

并将其保存到一个变量中，我该怎么做？我一直在查看 PHP 手册，但无法解决

Answer 1

preg_match('~^(Expires:.+?)$~ism', $headers, $result);

return $result[1];