PHP contains many predefined variables from these predefined variables many are superglobals, It means that we can access all these variables from any function,file or class without having any problem.
Below are some PHP superglobal variables:-
- $GLOBALS
- $_SERVER
- $_REQUEST
- $_POST
- $_GET
PHP $GLOBALS
$GLOBALS is a part of superglobal variables . It is use for accessing global variables.
eg
<?php
$a = 5;
$b = 10;
function add() {
$GLOBALS['c'] = $GLOBALS['a'] + $GLOBALS['b'];
}
add();
echo $c;
?>
In the above example c is a global variable which is contain within the $GLOBALS array, so we can access it from outside the function.
PHP $_SERVER
$_SERVER contains information about headers, paths, and script.
eg:-
<?php
echo $_SERVER['SERVER_NAME'];
echo "<br>";
echo $_SERVER['HTTP_HOST'];
echo "<br>";
echo $_SERVER['HTTP_USER_AGENT'];
echo "<br>";
echo $_SERVER['SCRIPT_NAME'];
?>
PHP $_REQUEST
PHP $_REQUEST variable will help us in collecting information when we submit an HTML form.
<html>
<body>
<form method="post" action="<?php echo $_SERVER['PHP_SELF'];?>">
Name: <input type="text" name="firstname">
<input type="submit">
</form>
<?php
if ($_SERVER["REQUEST_METHOD"] == "POST") {
// collect value of input field
$name = $_REQUEST['firstname'];
if (empty($name)) {
echo "Name is empty";
} else {
echo $name;
}
}
?>
</body>
</html>
PHP $_POST
when we submit html form with post method than $_post is used to pass variables.
eg:-
<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>
PHP $_GET
when we submit html form with GET method than $_GET is used to pass variables.
<html>
<body>
<?php
echo "name " $_GET['fname']];
?>
</body>
</html>
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