<!DOCTYPE html>
<html>
<body>
<?php
$x = 75;
$y = 25;
function addition()
{
$GLOBALS['z'] = $GLOBALS['x'] + $GLOBALS['y'];
}
addition();
echo $z;
?>
</body>
</html>
![](https://img2018.cnblogs.com/blog/1020928/201905/1020928-20190529180812964-1951675501.png)
<!DOCTYPE html>
<html>
<body>
<?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'];
?>
</body>
</html>
![](https://img2018.cnblogs.com/blog/1020928/201905/1020928-20190529180853766-1844450771.png)
<!DOCTYPE html>
<html>
<body>
<form method="post" action="<?php echo $_SERVER['PHP_SELF'];?>">
Name: <input type="text" name="fname">
<input type="submit">
</form>
<?php
$name = htmlspecialchars($_REQUEST['fname']);
echo $name;
?>
</body>
</html>
![](https://img2018.cnblogs.com/blog/1020928/201905/1020928-20190529181026222-1588981657.png)
<!DOCTYPE html>
<html>
<body>
<a href="test_get.php?subject=PHP&web=runoob.com">测试 $_GET</a>
</body>
</html>
![](https://img2018.cnblogs.com/blog/1020928/201905/1020928-20190530090503978-901608291.png)