Introduction to the difference between $_GET $_POST $_REQUEST in PHP_PHP tutorial

Introduction to the difference between $_GET $_POST $_REQUEST in PHP

There are $_REQUEST, $_POST and $_GET in PHP for accepting form data.

1. The differences and characteristics of $_REQUEST, $_POST and $_GET

$_REQUEST[] has the functions of $_POST[] $_GET[], but $_REQUEST[] is slower. All data submitted through the POST and GET methods are available through the $_REQUEST array.

2. Differences and characteristics of $_POST and $_GET

1. GET is to obtain data from the server, and POST is to transmit data to the server.
2. GET adds the parameter data queue to the URL pointed to by the ACTION attribute of the submitted form. The values ​​correspond to each field in the form one-to-one and can be seen in the URL. POST uses the HTTP POST mechanism to place each field in the form and its content in the HTML HEADER and transmit it to the URL address pointed to by the ACTION attribute. Users cannot see this process.
3. For GET method to submit form data, the server side uses $_GET['name'] to obtain the value of the variable. For POST method to submit form data, the server side uses $_POST['name'] to obtain the submitted data. Of course, both Form data can be obtained through $_REQUEST['name']. For submitting form data in REQUEST mode, the server uses $_REQUEST[‘name’] to obtain the value of the variable, but this method is rarely used.
4. The amount of data transmitted by GET is small and cannot be larger than 2KB. The amount of data transmitted by POST is large and is generally unrestricted by default. But in theory, it is generally believed that it cannot exceed 100KB.
5. GET has very low security, while POST has high security.
6. The GET form value can be obtained through _GET; however, the parameters set through the action URL cannot always be obtained,

and< form method="get"action="a.asp"> is the same, that is to say, in this case, the GET method will ignore the parameter list following the action page. The POST form value can be obtained through _POST; but the parameters set through the url parameter of the action may not be obtained through _POST. action=test.php?id=1 is the GET method to pass the value. You can use $_REQUEST and $_GET to accept the value, but you cannot use the POST method to obtain the value, even if the form is submitted in the POST method. When submitting a form, if there are parameters in the action, it is best to use the POST form method. For the data in the form, obtain it directly through POST. For the parameters in the action, obtain it through GET.
When doing data query, it is recommended to use the GET method, and when doing data addition, modification or deletion, it is recommended to use the POST method.
Request reads get first and then post. They exist at the same time, that is, the previous variables are overwritten.

Classic example:

echo "get＼n";
print_r($_GET);
echo "post＼n";
print_r($_POST);
echo "request＼n";
print_r($_REQUEST);
?>
< form method=post action='?a=1&b=2'>
< input type=text name=a value='a'>
< input type=text name=b value='b'>
< input type=submit value=test>
< /form>

Output result:

get:
Array
(
[a] => 1
[b] => 2
)
post:
Array
(
[a] => a
[b] => b
)
request：
Array
(
[a] => a
[b] => b
)

In fact, there is a setting item in the php configuration file php.ini: variables_order = "GPCS". GPCS is the abbreviation of GET, POST, Cookie, and Server respectively. Variables_order = "GPCS" means the parsing order of variables in the php file. Are GET, POST, Cookie and Server.

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