PHP detects whether remote file exists_PHP tutorial

Briefly explain the above code. The function of get_headers is to access a remote address and return the HTTP headers sent by the server in the form of an array. And $header[0] is the status code returned by the server (if nothing else happens, the status code should be the first one returned).

To determine that a file exists on the remote server, just make sure that the status code returned by accessing the file is "HTTP/1.1 200 OK" (of course you can also determine if the status code is not "HTTP/1.1 404 Not Found") Then the file exists, but it always feels unsafe. After all, there are other status codes such as 301, 400).

Example of obtaining three-digit HTTP response code:

function get_http_response_code($theURL) {

$headers = get_headers($theURL);

Return substr($headers[0], 9, 3);

}

?>

Example of excluding redirects:

/**

* Fetches all the real headers sent by the server in response to a HTTP request without redirects

* Get headers without redirection

​*/

function get_real_headers($url,$format=0,$follow_redirect=0) {

if (!$follow_redirect) {

//set new default options

$opts = array('http' =>

array('max_redirects'=>1,'ignore_errors'=>1)

);

Stream_context_get_default($opts);

}

//get headers

$headers=get_headers($url,$format);

//restore default options

if (isset($opts)) {

$opts = array('http' =>

array('max_redirects'=>20,'ignore_errors'=>0)

);

Stream_context_get_default($opts);

}

//return

Return $headers;

}

?>

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http://www.bkjia.com/PHPjc/478544.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/478544.htmlTechArticleBriefly explain the above code. The function of get_headers is to access a remote address and return the HTTP headers sent by the server in the form of an array. And $header[0] is the status returned by the server...