YouTip

PHP has several special variables, known as "superglobals," which are always accessible in all scopes. These superglobals are listed below: * `$GLOBALS` * `$_SERVER` * `$_GET` * `$_POST` * `$_FILES` * `$_COOKIE` * `$_SESSION` * `$_REQUEST` * `$_ENV` --- ### $GLOBALS `$GLOBALS` is a PHP superglobal variable that is used to access global variables from anywhere in the script, including functions and classes. The following example demonstrates how to use the `$GLOBALS` variable: ```php In the example above, `$z` is a global variable because it is declared outside the function, but it can be accessed inside the function using `$GLOBALS['z']`. --- ### $_SERVER `$_SERVER` is a PHP superglobal variable that contains information about headers, paths, and script locations. The following table lists the most important elements of `$_SERVER`: | Element/Code | Description | | :--- | :--- | | `$_SERVER['PHP_SELF']` | The filename of the currently executing script, relative to the document root. | | `$_SERVER['SERVER_NAME']` | The name of the server host under which the current script is running. | | `$_SERVER['SERVER_SOFTWARE']` | The server identification string, e.g., "Apache/2.4.18". | | `$_SERVER['REQUEST_METHOD']` | The method used to access the page, e.g., "GET", "HEAD", "POST", or "PUT". | | `$_SERVER['QUERY_STRING']` | The query string, if any, via which the page was accessed. | | `$_SERVER['DOCUMENT_ROOT']` | The document root directory under which the current script is executing, as defined in the server's configuration file. | The following example demonstrates the use of `$_SERVER`: ```php <?php echo $_SERVER['PHP_SELF']; echo "
"; echo $_SERVER['SERVER_NAME']; echo "
"; echo $_SERVER['HTTP_HOST']; echo "
"; echo $_SERVER['HTTP_REFERER']; echo "
"; echo $_SERVER['HTTP_USER_AGENT']; echo "
"; echo $_SERVER['SCRIPT_NAME']; ?> --- ### $_GET `$_GET` is a PHP superglobal variable used to collect data sent via the HTTP GET method. Data is visible in the URL. The following example shows how to send data using the GET method: Name: Age: When the user clicks the "Submit" button, the URL sent to the server will be: `test.php?fname=Peter&age=37` The following example uses the `$_GET` variable to display the received data: ```php <?php echo "Name: " . $_GET['fname'] . "
"; echo "Age: " . $_GET['age']; ?> --- ### $_POST `$_POST` is a PHP superglobal variable used to collect data sent via the HTTP POST method. Data is not visible in the URL. The following example shows how to send data using the POST method: Name: Age: When the user clicks the "Submit" button, the URL sent to the server will be: `test.php` The data is not visible in the URL. The following example uses the `$_POST` variable to display the received data: ```php <?php echo "Name: " . $_POST['fname'] . "
"; echo "Age: " . $_POST['age']; ?> --- ### $_REQUEST `$_REQUEST` is a PHP superglobal variable used to collect data after submitting an HTML form using both the GET and POST methods. The following example uses the `$_REQUEST` variable to display the received data: ```php <?php echo "Name: " . $_REQUEST['fname'] . "
"; echo "Age: " . $_REQUEST['age']; ?>