Predefined variables - PHP manual notes

Predefined variables represent all external variables as built-in environment variables, and error information as return headers. Superglobal variables are built-in variables that are always available in all scopes. They can be accessed within a function or method without executing global $variable.

$GOBALS refers to all variables available in the global scope, which are always available in PHP.

$_SERVERServer and execution environment information, this contains more array elements, such as $_SERVER['PHP_SELFT'], $_SERVER['SCRIPT_FILENAME'], $_SERVER['SERVER_NAME'], etc. . The items in this array are created by the web server, and every server is not guaranteed to serve all items.

$_GETAn array of variables passed to the current script via URL parameters.

$_POSTAn array of variables passed to the current script via the HTTP POST method.

$_FILESAn array of files uploaded to the current script via HTTP POST.

$_REQUESTBy default, it contains arrays of $_GET, $_POST and $_COOKIE. When running in command line mode, the argv and argc information will not be included, they will exist in the $_SERVER array. The items of this array and their order depend on the configuration of PHP's variables_order directive.

$_SESSIONThe current script can use the array of SESSION variables to start a new session or reuse an existing session through session_start().

$_ENVAn array of variables passed to the current script through the environment. These variables are imported from the running environment of the PHP parser into the global namespace of PHP.

$_COOKIEAn array of variables passed to the current script through HTTP Cookies. Cookies can be set on the client through setcookie().

$php_errormsgContains the latest error message generated by PHP and is only available in the scope where the error occurred.

$HTTP_RAW_POST_DATAContains the raw data submitted by POST.

$http_response_header contains the HTTP response header. Why was the test not successful in my system?

$argc contains the number of arguments passed to the current script when running from the command line. The minimum value is 1. Only available when regiser_argc_argv is turned on.

$argv contains an array of arguments passed to the current script when running from the command line. The first argument is always the filename of the current script.

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