Global Variable in PHP
Super Global Variable in PHP
Some pre-defined variables are available in php which is know as superglobals variable, which means that they are always accessible, regardless of scope - and you can access them from any function, class or file without having to do anything special.
List of superglobal variables are give below;
- $GLOBALS
- $_SERVER
- $_REQUEST
- $_POST
- $_GET
- $_FILES
- $_ENV
- $_COOKIE
- $_SESSION
$GLOBALS variable
$GLOBALS is a PHP super global variable which is used to access global variables from anywhere in the PHP script (also from within functions or methods). Using $GLOBALS[index] stores all global variables in an array. Here index hold all variable.
$GLOBALS Example
<?php $x = 75; $y = 25; function addition() { $GLOBALS['z'] = $GLOBALS['x'] + $GLOBALS['y']; } addition(); echo $z; ?>
$_SERVER Variable
$_SERVER is a PHP super global variable which holds information about headers, paths, and script locations.
$_SERVER Example
<?php echo $_SERVER['PHP_SELF']; echo "<br>"; echo $_SERVER['SERVER_NAME']; echo "<br>"; echo $_SERVER['HTTP_HOST']; echo "<br>"; echo $_SERVER['HTTP_REFERER']; echo "<br>"; echo $_SERVER['HTTP_USER_AGENT']; echo "<br>"; echo $_SERVER['SCRIPT_NAME']; ?>
$_REQUEST Variable
PHP $_REQUEST is used to collect data after submitting an HTML form.
$_REQUEST Example
<html> <body> <form method="post" action="<?php echo $_SERVER['PHP_SELF'];?>"> Name: <input type="text" name="fname"> <input type="submit"> </form> <?php if ($_SERVER["REQUEST_METHOD"] == "POST") { // collect value of input field $name = $_REQUEST['fname']; if (empty($name)) { echo "Name is empty"; } else { echo $name; } } ?> </body> </html>
$_POST Variable
PHP $_POST is widely used to collect form data after submitting an HTML form with method="post". $_POST is also widely used to pass variables.
$_POST Example
<html> <body> <form method="post" action="<?php echo $_SERVER['PHP_SELF'];?>"> Name: <input type="text" name="fname"> <input type="submit"> </form> <?php if ($_SERVER["REQUEST_METHOD"] == "POST") { // collect value of input field $name = $_POST['fname']; if (empty($name)) { echo "Name is empty"; } else { echo $name; } } ?> </body> </html>
$_GET Variable
PHP $_GET can also be used to collect form data after submitting an HTML form with method="get".
$_GET Example
<html> <body> <a href="test_get.php?subject=PHP&web=W3schools.com">Test $GET</a> </body> </html>
$_FILES Variable
The PHP global $_FILES contains all the information of file. By the help of $_FILES global, we can get file name, file type, file size, temp file name and errors associated with file.
$_FILES Example
<!DOCTYPE html> <html> <body> <form action="uploader.php" method="post" enctype="multipart/form-data"> Select File: <input type="file" name="fileToUpload"/> <input type="submit" value="Upload Image" name="submit"/> </form> <?php $target_path = "c:/"; $target_path = $target_path.basename( $_FILES['fileToUpload']['name']); if(move_uploaded_file($_FILES['fileToUpload']['tmp_name'], $target_path)) { echo "File uploaded successfully!"; } else { echo "Sorry, file not uploaded, please try again!"; } ?> <body> <html>
$_ENV Variable
$_ENV global variable in php is a predefined reserved variable that contains an array of information related to the environment in which php script is running.
$_ENV Example
<?php echo 'My username is ' .$_ENV["USER"] . '!'; ?>
$_COOKIE Variable
$_COOKIE is used to create cookie.
$_COOKIE Example
<?php $cookie_name = "user"; $cookie_value = "Hitesh Kumar"; setcookie($cookie_name, $cookie_value, time() + (86400 * 30), "/"); // 86400 = 1 day ?> <!DOCTYPE html> <html> <body> <?php if(!isset($_COOKIE[$cookie_name])) { echo "Cookie named '" . $cookie_name . "' is not set!"; } else { echo "Cookie '" . $cookie_name . "' is set!
"; echo "Value is: " . $_COOKIE[$cookie_name]; } ?> <body> <html>
$_SESSION Variable
$_SESSION Variable is used to create session.
$_SESSION Example
<?php // Start the session session_start(); ?> <!DOCTYPE html> <html> <body> <?php // Set session variables $_SESSION["favcolor"] = "green"; $_SESSION["favanimal"] = "cat"; echo "Session variables are set."; ?> <body> <html>