Session variables in PHP - Interactive Code 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()

Bstart_session()

Csession_begin()

Dbegin_session()

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect function names like start_session() or session_begin().

Forgetting the parentheses after the function name.

In PHP, session_start() is used to start a session or resume the current one.

2fill in blank

medium

Complete the code to set a session variable named 'user' with value 'Alice'.

PHP

<?php
session_start();
$_SESSION[[1]] = 'Alice';
?>

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

Auser_name

Buser

C'user'

D"user"

Attempts:

3 left

💡 Hint

Common Mistakes

Not using quotes around the session key.

Using a different key name than 'user'.

Session keys must be strings, so use quotes around 'user'.

3fill in blank

hard

Fix the error in the code to correctly retrieve the session variable 'user'.

PHP

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

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

A['

B["

C']

D{

Attempts:

3 left

💡 Hint

Common Mistakes

Using parentheses or curly braces instead of square brackets.

Not using quotes around the key.

Session variables are accessed using square brackets and quotes around the key.

4fill in blank

hard

Fill both blanks to check if a session variable 'loggedIn' is set and true.

PHP

<?php
session_start();
if (isset($_SESSION[1]loggedIn[2]) && $_SESSION['loggedIn'] === true) {
    echo 'Welcome!';
}
?>

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

A['

B"

C']

D)

Attempts:

3 left

💡 Hint

Common Mistakes

Using parentheses or missing quotes.

Using double quotes inconsistently.

Use square brackets with quotes to check if the session variable exists.

5fill in blank

hard

Fill all three blanks to unset the session variable 'cart', destroy the session, and redirect to 'index.php'.

PHP

<?php
session_start();
unset($_SESSION[1]cart[2]);
session[3]();
header('Location: index.php');
exit();
?>

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

A['

B']

Cdestroy

Dclose

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong brackets or missing quotes in unset.

Using session_close() instead of session_destroy().

To remove a session variable, use unset($_SESSION['cart']). To end the session, use session_destroy().

Practice

1. What is the main purpose of using session_start() in PHP?

easy

A. To connect to a database

B. To send output to the browser

C. To begin a session and enable session variables

D. To include another PHP file

Solution

1. Step 1: Understand what session_start() does

   This function initializes a session or resumes the current one based on a session identifier passed via a cookie or URL.

2. Step 2: Identify the purpose of session variables

   Session variables store user data across multiple pages, but they only work if a session is started first.

3. Final Answer:

   To begin a session and enable session variables -> Option C

4. Quick Check:

   session_start() = start session [OK]

Hint: Remember: session_start() must be called before using $_SESSION [OK]

Common Mistakes:

• Thinking session_start() connects to a database
• Using session variables without calling session_start()
• Confusing session_start() with output functions

2. Which of the following is the correct way to set a session variable named user with the value "Alice"?

easy

A. $_SESSION['user'] = 'Alice';

B. session['user'] = 'Alice';

C. set_session('user', 'Alice');

D. session_start['user'] = 'Alice';

Solution

1. Step 1: Recall the syntax for setting session variables

   Session variables are stored in the global $_SESSION array, so you assign values like $_SESSION['key'] = value;.

2. Step 2: Check each option's syntax

   $_SESSION['user'] = 'Alice'; uses the correct $_SESSION superglobal with proper array syntax and assignment.

3. Final Answer:

   $_SESSION['user'] = 'Alice'; -> Option A

4. Quick Check:

   $_SESSION['key'] = value [OK]

Hint: Use $_SESSION['name'] = value to set session data [OK]

Common Mistakes:

• Using session without the $_SESSION superglobal
• Trying to call session_start as an array
• Using undefined functions like set_session()

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

session_start();
$_SESSION['count'] = 1;
$_SESSION['count']++;
echo $_SESSION['count'];

medium

A. 1

B. 0

C. Error

D. 2

Solution

1. Step 1: Analyze session variable initialization and increment

   The code sets $_SESSION['count'] to 1, then increments it by 1 using ++.

2. Step 2: Determine the final value of $_SESSION['count']

   After increment, the value becomes 2, which is then printed by echo.

3. Final Answer:

   2 -> Option D

4. Quick Check:

   1 incremented by 1 = 2 [OK]

Hint: Increment session variable with ++ after setting it [OK]

Common Mistakes:

• Forgetting to call session_start() before using $_SESSION
• Assuming $_SESSION['count'] stays 1 after ++
• Expecting an error due to session usage

4. Identify the error in this PHP code snippet:

$_SESSION['user'] = 'Bob';
echo $_SESSION['user'];

medium

A. Missing session_start() before using $_SESSION

B. Incorrect array syntax for $_SESSION

C. Cannot assign string to $_SESSION

D. Echo statement syntax is wrong

Solution

1. Step 1: Check for session initialization

   The code uses $_SESSION but does not call session_start() first, which is required to access session variables.

2. Step 2: Verify syntax correctness

   The array syntax and echo statement are correct, and assigning a string to $_SESSION is valid.

3. Final Answer:

   Missing session_start() before using $_SESSION -> Option A

4. Quick Check:

   Always call session_start() before $_SESSION [OK]

Hint: Always start session with session_start() before $_SESSION use [OK]

Common Mistakes:

• Using $_SESSION without session_start()
• Thinking $_SESSION needs special syntax
• Assuming echo syntax is incorrect

5. You want to count how many times a user visits a page during a session. Which code snippet correctly implements this using session variables?

hard

A. session_start();
$_SESSION['visits']++;
echo $_SESSION['visits'];

B. session_start();
if (!isset($_SESSION['visits'])) {
$_SESSION['visits'] = 1;
} else {
$_SESSION['visits']++;
}
echo $_SESSION['visits'];

C. session_start();
$_SESSION['visits'] = 1;
echo $_SESSION['visits'];

D. if (!isset($_SESSION['visits'])) {
$_SESSION['visits'] = 1;
} else {
$_SESSION['visits']++;
}
echo $_SESSION['visits'];

Solution

1. Step 1: Ensure session is started

   Calling session_start() is necessary to use session variables.

2. Step 2: Check visit count logic

   The code checks if $_SESSION['visits'] exists; if not, it sets it to 1. Otherwise, it increments the count. This correctly tracks visits.

3. Step 3: Verify output

   Finally, it echoes the current visit count, showing how many times the user visited during the session.

4. Final Answer:

   Code snippet with session_start() and visit count check -> Option B

5. Quick Check:

   Initialize then increment visits with session_start() [OK]

Hint: Always check isset() before incrementing session counters [OK]

Common Mistakes:

• Forgetting session_start() before using $_SESSION
• Not checking if session variable exists before increment
• Resetting visit count every page load