Session vs cookie decision in PHP - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to start a session in PHP.

PHP

<?php
[1]();
?>

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

Asession_start

Bcookie_start

Cstart_session

Dinit_session

Attempts:

3 left

💡 Hint

Common Mistakes

Using cookie_start() instead of session_start()

Misspelling the function name

In PHP, session_start() is used to begin a session.

2fill in blank

medium

Complete the code to set a cookie named 'user' with value 'Alice' that expires in 1 hour.

PHP

<?php
setcookie('user', 'Alice', time() [1] 3600);
?>

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

A-

B/

C*

D+

Attempts:

3 left

💡 Hint

Common Mistakes

Using subtraction which sets expiration in the past

Using multiplication or division which is incorrect here

To set a cookie expiration 1 hour from now, add 3600 seconds to current time.

3fill in blank

hard

Fix the error in the code to check if a cookie named 'user' exists.

PHP

<?php
if (isset($_COOKIE[1])) {
    echo 'User cookie is set';
}
?>

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

A{'user'}

B('user')

C['user']

D<'user'>

Attempts:

3 left

💡 Hint

Common Mistakes

Using parentheses or curly braces instead of square brackets

Not quoting the cookie name

To access a cookie value, use square brackets with the cookie name as a string key.

4fill in blank

hard

Fill both blanks to store and retrieve a session variable named 'username'.

PHP

<?php
session_start();
$_SESSION[1] = 'Bob';
echo $_SESSION[2];
?>

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

A['username']

B('username')

C{'username'}

D<'username'>

Attempts:

3 left

💡 Hint

Common Mistakes

Using parentheses or curly braces instead of square brackets

Not quoting the key name

Session variables are accessed using square brackets with the variable name as a string.

5fill in blank

hard

Fill all three blanks to decide when to use a session or a cookie for storing user data.

PHP

<?php
// Use session when data is [1] and cookie when data is [2]
// Example:
if ($data_is_sensitive) {
    session_start();
    $_SESSION[3] = 'secret';
} else {
    setcookie('info', 'public', time() + 3600);
}
?>

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

Atemporary

Bpersistent

Csecure

Dnon-sensitive

E['user_data']

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing when to use session vs cookie

Incorrect syntax for session variable key

Sessions are used for secure (sensitive) data that should not persist on client side. Cookies are for non-sensitive data that can persist.

The session variable key should be a string in square brackets.

Practice

1. Which of the following is the best reason to use a PHP session instead of a cookie?

easy

A. To reduce server memory usage

B. To save user preferences permanently on the browser

C. To store sensitive user data temporarily during a visit

D. To share data between different websites

Solution

1. Step 1: Understand session purpose

   Sessions store data on the server and are good for sensitive or temporary data during a visit.

2. Step 2: Compare with cookies

   Cookies store data on the user's browser and are better for non-sensitive, longer-term data.

3. Final Answer:

   To store sensitive user data temporarily during a visit -> Option C

4. Quick Check:

   Session = temporary sensitive data [OK]

Hint: Use sessions for sensitive, temporary data; cookies for long-term [OK]

Common Mistakes:

• Thinking cookies are safer than sessions
• Using sessions to store permanent data
• Confusing where data is stored

2. Which PHP code snippet correctly starts a session?

easy

A.

B.

C.

D.

Solution

1. Step 1: Recall PHP session syntax

   The correct function to start a session is session_start().

2. Step 2: Check other options

   Other options are not valid PHP functions and will cause errors.

3. Final Answer:

   <?php session_start(); ?> -> Option D

4. Quick Check:

   session_start() starts session [OK]

Hint: Remember exact function name: session_start() [OK]

Common Mistakes:

• Using incorrect function names
• Forgetting parentheses
• Confusing session_start with cookie functions

3. What will be the output of this PHP code?

<?php
session_start();
$_SESSION['user'] = 'Alice';
setcookie('user', 'Bob', time() + 3600);
echo $_SESSION['user'] . ' & ' . $_COOKIE['user'];
?>

medium

A. Alice &

B. Bob & Alice

C. Alice & Alice

D. Bob & Bob

Solution

1. Step 1: Understand session and cookie values

   $_SESSION['user'] is set to 'Alice'. The cookie 'user' is set to 'Bob' but will be available on the next request only.

2. Step 2: Check echo output

   $_SESSION['user'] outputs 'Alice'. $_COOKIE['user'] is not set in this request (assuming no prior cookie), so it is empty. Output: Alice & (empty).

3. Final Answer:

   Alice & -> Option A

4. Quick Check:

   Session = Alice immediate, Cookie = next request [OK]

Hint: Session changes immediate; cookie available next request [OK]

Common Mistakes:

• Expecting cookie value immediately after setcookie()
• Mixing session and cookie values
• Assuming cookie overwrites session

4. Identify the error in this PHP code snippet:

<?php
setcookie('theme', 'dark');
session_start();
$_SESSION['theme'] = 'light';
?>

medium

A. session_start() must be called before setcookie()

B. No error, code is correct

C. $_SESSION cannot be set after setcookie()

D. setcookie() must be called before any output

Solution

1. Step 1: Recall header rules in PHP

   Both setcookie() and session_start() send HTTP headers and must be called before any output.

2. Step 2: Check order and output

   No output before either function. Order of setcookie() before session_start() is fine; multiple Set-Cookie headers are allowed.

3. Final Answer:

   No error, code is correct -> Option B

4. Quick Check:

   Headers before output, order OK [OK]

Hint: Call setcookie() and session_start() before any output [OK]

Common Mistakes:

• Thinking session_start() must come before setcookie()
• Ignoring header output rules
• Assuming $_SESSION depends on setcookie()

5. You want to remember a user's language preference safely for their entire visit but not after they close the browser. Which is the best choice?

hard

A. Store language in a session variable

B. Store language in a cookie with 1 year expiry

C. Store language in a cookie without expiry

D. Store language in a hidden form field

Solution

1. Step 1: Understand data lifetime needs

   The language preference should last only during the visit, not after browser closes.

2. Step 2: Match storage type to lifetime

   Sessions last until browser closes or session expires, so session variable fits. Cookies persist beyond browser close if expiry is set.

3. Final Answer:

   Store language in a session variable -> Option A

4. Quick Check:

   Temporary visit data = session [OK]

Hint: Use session for visit-only data, cookie for longer storage [OK]

Common Mistakes:

• Using cookies for temporary visit data
• Setting cookie without expiry expecting session behavior
• Using hidden fields for persistent data