PHP $_REQUEST array security risks_PHP tutorial

Everyone knows that using $_REQUEST can directly eliminate the need to judge posts and get some codes, making it easier to use. However, if we want to think about it in detail, we will feel that $_REQUEST is too scary. See the analysis below.

We all know that to process form data, you can use PHP's two super-global variables $_GET and $_POST, which one is specified by the method when the form is submitted. In addition, PHP also provides us with the $_REQUEST array. But it not only contains all the data elements of $_GET and $_POST, but also contains all the data elements of the super-global array $_COOKIE.
But have you ever thought about it, if the keys in these three arrays are the same, then which array value do I get using $_REQUEST? Will there be any problems?
I use the following code to demonstrate for everyone. Because I just want to explain the problem, $_COOKIE is not set here. Please handle it yourself:

The code is as follows  代码如下 复制代码 var_dump($_GET['a'],$_POST['a'],$_REQUEST['a']); ?>	Copy code
var_dump($_GET['a'],$_POST['a'],$_REQUEST['a']); ?>  代码如下 复制代码 ; This directive describes the order in which PHP registers GET, POST, Cookie, ; Environment and Built-in variables (G, P, C, E & S respectively, often ; referred to as EGPCS or GPC).  Registration is done from left to right, newer ; values override older values. variables_order = "EGPCS"