PHP Common syntax functions ____ functions

Empty and Isset

Empty () to determine whether a variable is "null", Isset () to determine whether a variable has been set.

The empty also detects whether the variable is empty and zero. When a variable value is 0,empty (), the variable equals null, which is equivalent to no setting.

Parse_url

Official http://www.php.net/manual/zh/function.parse-url.php

parse_url-resolves the URL and returns its components

The explode () function splits the string into arrays.

Official http://www.w3school.com.cn/php/func_string_explode.asp

Unset-frees the given variable

http://www.php.net/manual/zh/function.unset.php

$_server

Official http://www.php.net/manual/zh/reserved.variables.server.php

$_server is an array that contains information such as header information (header), path (path), and script location (scripts locations), and so on. The items in this array are created by the WEB server. There is no guarantee that every server will provide all the items;