Why superglobals exist in PHP - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to access the value of a GET parameter named 'user'.

PHP

$username = $_[1]['user'];

Drag options to blanks, or click blank then click option'

ACOOKIE

BPOST

CSESSION

DGET

Attempts:

3 left

💡 Hint

Common Mistakes

Using $_POST instead of $_GET for URL parameters.

Trying to access $_SESSION without starting a session.

$_GET is a superglobal array in PHP that holds data sent via URL parameters.

2fill in blank

medium

Complete the code to set a session variable named 'loggedIn' to true.

PHP

session_start();
$_[1]['loggedIn'] = true;

Drag options to blanks, or click blank then click option'

ASESSION

BPOST

CCOOKIE

DGET

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting to call session_start() before accessing $_SESSION.

Using $_POST or $_GET instead of $_SESSION for session data.

$_SESSION is a superglobal used to store session data across pages.

3fill in blank

hard

Fix the error in the code to correctly retrieve a cookie named 'theme'.

PHP

$theme = $_[1]['theme'];

Drag options to blanks, or click blank then click option'

ASESSION

BCOOKIE

CPOST

DGET

Attempts:

3 left

💡 Hint

Common Mistakes

Using $_SESSION or $_POST to access cookie data.

Trying to access cookies without checking if they exist.

$_COOKIE is the superglobal array that holds cookie data sent by the browser.

4fill in blank

hard

Fill both blanks to create an array that holds input data from POST and COOKIE.

PHP

$allData = array_merge($_[1], $_[2]);

Drag options to blanks, or click blank then click option'

AGET

BPOST

CCOOKIE

DSESSION

Attempts:

3 left

💡 Hint

Common Mistakes

Using $_GET instead of $_POST for form data.

Including $_SESSION which is not input data.

$_POST and $_COOKIE are superglobals that hold form data and cookie data respectively. Merging them combines input sources.

5fill in blank

hard

Fill all three blanks to check if a POST parameter 'email' exists and is not empty.

PHP

if (isset($_[1]['email']) && $_[2]['email'] [3] '') {
    echo 'Email received';
}

Drag options to blanks, or click blank then click option'

APOST

C!=

DGET

Attempts:

3 left

💡 Hint

Common Mistakes

Using $_GET instead of $_POST for form data.

Using '==' instead of '!=' to check for non-empty value.

Use $_POST to check the 'email' parameter. The operator '!=' checks that the value is not empty.

Practice

1. Why do superglobals exist in PHP?

easy

A. To provide easy access to important data like user input and server info anywhere in the code

B. To make PHP run faster by compiling variables

C. To store temporary files on the server

D. To replace functions with variables

Solution

1. Step 1: Understand the purpose of superglobals

   Superglobals are special variables that PHP makes available everywhere without needing to pass them around.

2. Step 2: Identify what superglobals provide

   They give easy access to user input, session data, and server info, simplifying code and organization.

3. Final Answer:

   To provide easy access to important data like user input and server info anywhere in the code -> Option A

4. Quick Check:

   Superglobals = easy access everywhere [OK]

Hint: Superglobals give global access to key data without extra code [OK]

Common Mistakes:

• Thinking superglobals speed up PHP execution
• Confusing superglobals with temporary file storage
• Believing superglobals replace functions

2. Which of the following is the correct way to access the superglobal that holds form data sent via POST method?

easy

A. $post_data

B. $_POST

C. $POST

D. post_data

Solution

1. Step 1: Recall PHP superglobal syntax

   Superglobals start with a dollar sign and an underscore, like $_POST.

2. Step 2: Identify the correct superglobal for POST data

   $_POST is the built-in superglobal that holds form data sent via POST.

3. Final Answer:

   $_POST -> Option B

4. Quick Check:

   POST form data = $_POST [OK]

Hint: Superglobals always start with $_ and uppercase letters [OK]

Common Mistakes:

• Using $POST without underscore
• Using lowercase variable names
• Forgetting the dollar sign

3. What will the following PHP code output?

<?php
$_GET['name'] = 'Alice';
echo $_GET['name'];
?>

medium

A. Array

B. name

C. Alice

D. Undefined index error

Solution

1. Step 1: Understand the $_GET superglobal usage

   $_GET is an array that holds URL query parameters. Here, we manually set 'name' to 'Alice'.

2. Step 2: Echo the value stored in $_GET['name']

   Since 'name' is set to 'Alice', echo outputs 'Alice'.

3. Final Answer:

   Alice -> Option C

4. Quick Check:

   $_GET['name'] = 'Alice' outputs Alice [OK]

Hint: Echoing $_GET['key'] prints its value if set [OK]

Common Mistakes:

• Expecting 'name' string instead of value
• Thinking $_GET is empty without URL parameters
• Confusing array output with string

4. Identify the error in this PHP code snippet:

<?php
echo $_SESSION['user'];
?>

Assuming session_start() was not called earlier.

medium

A. Undefined index 'user' error

B. Session not started error or warning

C. No error, code works fine

D. Syntax error due to missing semicolon

Solution

1. Step 1: Understand $_SESSION behavior

   $_SESSION is always available as an empty array if no session data is loaded; session_start() initializes session handling but does not set keys.

2. Step 2: Identify the specific error

   Since 'user' key is not set, accessing $_SESSION['user'] produces a "Notice: Undefined index: user" (undefined index error).

3. Final Answer:

   Undefined index 'user' error -> Option A

4. Quick Check:

   Accessing unset $_SESSION['user'] = undefined index [OK]

Hint: Always call session_start() before using $_SESSION [OK]

Common Mistakes:

• Assuming $_SESSION works without session_start()
• Confusing undefined index with session error
• Missing semicolon is not the issue here

5. You want to write a PHP script that reads a user's IP address and the request method (GET or POST) used to access the page. Which superglobals should you use together to get this information?

hard

A. $_ENV for IP and $_FILES for request method

B. $_GET for IP and $_POST for request method

C. $_SESSION for IP and $_COOKIE for request method

D. $_SERVER for IP and $_SERVER for request method

Solution

1. Step 1: Identify where IP address is stored

   $_SERVER['REMOTE_ADDR'] holds the user's IP address.

2. Step 2: Identify where request method is stored

   $_SERVER['REQUEST_METHOD'] holds the HTTP method used (GET, POST, etc.).

3. Step 3: Confirm both come from $_SERVER superglobal

   Both pieces of info are in $_SERVER, so using it twice is correct.

4. Final Answer:

   $_SERVER for IP and $_SERVER for request method -> Option D

5. Quick Check:

   IP and method both in $_SERVER [OK]

Hint: Use $_SERVER for server and request info like IP and method [OK]

Common Mistakes:

• Using $_GET or $_POST for IP address
• Confusing $_SESSION or $_COOKIE for request method
• Using $_ENV or $_FILES incorrectly