$_REQUEST behavior in PHP - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this PHP code using $_REQUEST?

Consider this PHP script receiving a GET request with URL parameters ?name=Alice&age=30. What will be the output?

PHP

<?php
$_GET['name'] = 'Alice';
$_GET['age'] = '30';
$_POST = [];
$_COOKIE = [];
$_REQUEST = array_merge($_COOKIE, $_POST, $_GET);
echo $_REQUEST['name'] . ' is ' . $_REQUEST['age'] . ' years old.';
?>

A Notice: Undefined index: name

B Alice is 30 years old.

C 30 is Alice years old.

D Empty output

💡 Hint

Remember that $_REQUEST contains data from $_GET, $_POST, and $_COOKIE.

The $_REQUEST array includes all GET, POST, and COOKIE variables. Since $_GET has name and age, $_REQUEST will have them too. So the output is "Alice is 30 years old."

❓ Predict Output

intermediate

What happens if a POST and GET parameter have the same name in $_REQUEST?

Given this PHP code snippet, what will be the output?

PHP

<?php
$_GET['color'] = 'blue';
$_POST['color'] = 'red';
$_COOKIE = [];
$_REQUEST = array_merge($_COOKIE, $_GET, $_POST);
echo $_REQUEST['color'];
?>

A red

B blue

C Notice: Undefined index: color

D Empty output

💡 Hint

Check the order PHP uses to populate $_REQUEST by default. Later sources override earlier ones.

By default, PHP populates $_REQUEST in the order of GPC (GET, POST, COOKIE), with later values overriding earlier ones. So the POST value 'red' overwrites the GET 'blue' in $_REQUEST. The output is 'red'.

🔧 Debug

advanced

Why does this code produce an undefined index error for $_REQUEST?

Look at this PHP code snippet:

<?php
if ($_REQUEST['user']) {
    echo 'User is set';
} else {
    echo 'User is not set';
}
?>

When no parameters are sent, it throws a notice: Undefined index: user. Why?

A Because $_REQUEST['user'] is accessed without checking if it exists first

B Because $_REQUEST is always empty

C Because PHP does not support $_REQUEST

D Because the code should use $_POST instead

💡 Hint

Think about how to safely check if an array key exists before using it.

Accessing $_REQUEST['user'] directly without checking if it exists causes a notice if the key is missing. Use isset($_REQUEST['user']) to avoid this.

❓ Predict Output

advanced

What is the output when $_COOKIE and $_GET have the same key in $_REQUEST?

Given this PHP code snippet:

<?php
$_GET['session'] = 'get_value';
$_COOKIE['session'] = 'cookie_value';
$_POST = [];
echo $_REQUEST['session'];
?>

What will it print?

A Notice: Undefined index: session

B Empty output

C cookie_value

D get_value

💡 Hint

Recall the default order of variables in $_REQUEST. Later sources override earlier.

PHP's default order for $_REQUEST is GET, POST, COOKIE, with later values overriding earlier ones. $_POST is empty, so COOKIE 'cookie_value' overrides GET 'get_value'. Output is 'cookie_value'.

🧠 Conceptual

expert

How can you change the order of variables in $_REQUEST?

PHP populates $_REQUEST using a default order of variables. Which PHP configuration directive controls this order?

A variables_order

B superglobals_order

C request_variables

D request_order

💡 Hint

Check php.ini settings related to request variables.

The request_order directive in php.ini controls the order in which GET, POST, and COOKIE variables populate $_REQUEST. If not set, variables_order is used as fallback.