Php study notes [pre-defined array (ultra-Global Array)]

Php learning notes pre-defined array (ultra-global array). For more information, see. The code is as follows:

/* Pre-defined array:
* Automatic global variable --- Super Global Array
*
* 1. contains data from WEB servers, clients, runtime environments, and user input.
* 2. These arrays are special.
* 3. These arrays can be used directly if they take effect automatically within the global range.
* 4. users cannot customize these arrays, but these arrays are operated in the same way as their own arrays.
* 5. You can directly use these arrays in functions.
*
* $ _ GET // variable submitted to the script through URL request
* $ _ POST // variables submitted to the script through the http post method
* $ _ REQUEST // variables submitted to the script through GET, POST, and COOKIE mechanisms
* $ _ FILES // variables submitted to the script by uploading FILES via the http post method
* $ _ COOKIE
* $ _ SESSION
* $ _ ENV // variables submitted to the script in the execution environment
* $ _ SERVER // The variable is set by the web server or directly associated with the execution environment of the current script.
* $ GLOBALS // as long as the variables are valid for the current script, the array key name is the name of the global script.
*
*
*/
// The Super Global array can be directly called within the function.
$ Arr = array (10, 20); // A general array
$ _ GET = array (50, 90); // A Super Global array
Function demo (){
Global $ arr; // you must include
Print_r ($ arr );
Print_r ($ _ GET); // You do not need to include a directly called ultra-global array.
}
?>

// Directly use the passed value as a variable, which is useful when register_global = on is in the php. ini configuration file.
Echo $ username ."
";
Echo $ email ."
";
Echo $ page ."
";
// The most stable value method
Echo $ _ GET ["username"]."
";
Echo $ _ GET ["email"]."
";
Echo $ _ GET ["page"]."
";
?>
This is a $ _ GET test


Print_r ($ _ GET); // cannot receive
Print_r ($ _ POST); // to receive
?>
// $ _ ENV usage
Echo'

'; 
print_r($_ENV); 
echo'

';
// Display the current environment
// You can also traverse
?>
// Use the $ GLOBALS ultra-global array to call global variables within the function
$ A = 100;
$ B = 200;
$ C = 300;
Function demo ()
{
// Directly call global variables
Echo $ GLOBALS ["a"]."
";
Echo $ GLOABLS ["B"]."
";
Echo $ GLOABLS ["c"]."
";
}
?>