Considerations for using PHP4.2.0 and later versions

From PHP 4.2.0 onwards, the default value of the PHP Command register_globals is off (in the php. ini configuration file). This is a major change in PHP. What is register_globals used? PHP is used to control whether the EGPCS (Environment, GET, POST, Cookie, Server) variables are registered as global variables. For example, for a http://www.xx.php? Var = 2 here var. When it is on, you only need to use $ var, but when it is off, you must use $ _ GET ["var"] to receive ~ $ _ GET is an array of PHP super global variables. Like this, $ GLOBALS includes a reference to a variable that is valid globally for each current script. The key of the array is the name of the global variable. $ GLOBALS array exists from PHP 3. $ _ SERVER variables are set by the Web SERVER or directly associated with the execution environment of the current script. It is equivalent to the old array $ HTTP_SERVER_VARS, but it is not a variable with $ _ SERVER, because PHP processes them differently, the same below. Although $ HTTP_SERVER_VARST and $ HTTP _ * _ VARS below can still be used, we do not recommend that you use $ HTTP _ * _ VARS. $ _ GET: variables submitted to the script through the http get method. For example, variables generated by the GET method of URLs and forms. Usage: $ _ GET ["xx"]; // the variable that is $ xx; the same as $ _ POST submitted to the script through the http post method. For example, a variable generated by the form POST method. Usage: $ _ POST ["xx"]; $ _ COOKIE variables submitted to the script through HTTP Cookies. For example, when reading the COOKIE value. $ _ FILES variables submitted to the script by uploading the http post file. My other article asp $ id = 22950 & page = 1 target = _ blank> describes the usage of the file upload process in detail, it is not described here. $ _ ENV: variables submitted to the script in the execution environment. $ _ REQUEST the variables submitted to the script through any user input mechanism, including GET, POST, and COOKIE. Therefore, this array is not trustworthy. $ _ SESSION: array of SESSION variables. You do not need to use session_regisger to register a variable. $ _ SESSION ["xx"] contains the preceding process. Do not post this post again. If you have any questions, start a new topic [br]. Thank you for your cooperation.