Introduction to the method of php get_headers to determine whether the URL is valid

Use php get_headers to determine the true validity of the url. For those who have not yet learned about the usage of the php get_headers function, you can refer to the article on this site: Explanation and usage of the php get_headers function. After understanding this function, you can know that this function will return the header information of an HTTP request. The information format is basically as follows: 1), Array ( [0] => HTTP/1.1 200 OK [1] => Date: Sat, 29 May 2004 12:28:13 GMT [2] => Server: Apache/1.3.27 (Unix) (Red-Hat/Linux) [3] => Last-Modified: Wed, 08 Jan 2003 23:11:55 GMT [4] => ETag: "3f80f-1b6-3e1cb03b" [5] => Accept-Ranges: bytes [6] => Content-Length: 438 [7] => Connection: close [8] => Content-Type: text/html )

2), Array ( [0] => HTTP/1.0 404 Not Found [1] => Date: Sat, 29 May 2004 12:28:13 GMT [2] => Server: Apache/1.3.27 (Unix) (Red-Hat/Linux) [3] => Last-Modified: Wed, 08 Jan 2003 23:11:55 GMT [4] => ETag: "3f80f-1b6-3e1cb03b" [5] => Accept-Ranges: bytes [6] => Content-Length: 438 [7] => Connection: close [8] => Content-Type: text/html )

Analysis: If it is judged whether the URL is valid or not, it is judged by the value of the first element in the array. The server returns 200, which means the file is returned correctly, and returns 404, which means the file does not exist. This makes it easy to determine whether a URL exists.

Many times, it is these small functions that help a lot. There are many good gadgets for obtaining header information. The principle is basically the same as this. It is recommended that you firmly grasp the usage of the get_headers() function.