How sessions work 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

Bstart_session

Cbegin_session

Dinit_session

Attempts:

3 left

💡 Hint

Common Mistakes

Using a function name that does not exist like start_session()

Forgetting to call the function before outputting HTML

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

2fill in blank

medium

Complete the code to store a value in the session.

PHP

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

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

Auser

BJohn

C"John"

D'user'

Attempts:

3 left

💡 Hint

Common Mistakes

Assigning a bare word without quotes which causes an error

Using single quotes around the key instead of the value

Session values must be assigned as strings or variables. Here, "John" is a string value stored in the session.

3fill in blank

hard

Fix the error in the code to correctly check if a session variable is set.

PHP

<?php
session_start();
if (isset([1]['user'])) {
    echo "User is logged in.";
}
?>

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

A$_session

B$SESSION

CSESSION

D$_SESSION

Attempts:

3 left

💡 Hint

Common Mistakes

Using lowercase or missing the dollar sign in $_SESSION

Using $SESSION or $session which are undefined

The correct superglobal array for sessions is $_SESSION with uppercase SESSION and a leading dollar sign.

4fill in blank

hard

Fill both blanks to correctly unset a session variable and destroy the session.

PHP

<?php
session_start();
unset([1]['user']);
[2]();
?>

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

A$_SESSION

Bsession_destroy

Cdestroy_session

D$SESSION

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong variable names like $SESSION

Calling a non-existent function like destroy_session()

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

5fill in blank

hard

Fill all three blanks to create a session variable, check it, and print it.

PHP

<?php
[1]();
if (isset([2]['count'])) {
    echo [3]['count'];
} else {
    echo "No count set.";
}
?>

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

Asession_start

B$_SESSION

Dsession_destroy

Attempts:

3 left

💡 Hint

Common Mistakes

Using session_destroy() instead of session_start()

Using different variable names for the session array

Start the session with session_start(). The session array is $_SESSION. Use it to check and print the 'count' variable.

Practice

1. What is the main purpose of using sessions in PHP?

easy

A. To remember user data across multiple pages

B. To store data permanently on the user's computer

C. To speed up the website loading time

D. To create a new database connection

Solution

1. Step 1: Understand what sessions do

   Sessions keep track of user information as they move between pages on a website.

2. Step 2: Compare options

   Only To remember user data across multiple pages correctly describes this purpose. Options A, C, and D describe unrelated functions.

3. Final Answer:

   To remember user data across multiple pages -> Option A

4. Quick Check:

   Sessions remember user data = B [OK]

Hint: Sessions remember data across pages, not store on user PC [OK]

Common Mistakes:

• Confusing sessions with cookies stored on user device
• Thinking sessions speed up page loading
• Believing sessions create database connections

2. Which PHP function must be called before using $_SESSION variables?

easy

A. session_end()

B. session_open()

C. session_init()

D. session_start()

Solution

1. Step 1: Identify the correct function to start a session

   The function session_start() initializes a session or resumes the current one.

2. Step 2: Check other options

   Functions like session_end(), session_open(), and session_init() do not exist in PHP.

3. Final Answer:

   session_start() -> Option D

4. Quick Check:

   Start session with session_start() = C [OK]

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

Common Mistakes:

• Using non-existent functions like session_end()
• Forgetting to call session_start() before $_SESSION
• Calling session_start() after outputting HTML

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

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

medium

A. 2

B. Error

C. 0

D. 1

Solution

1. Step 1: Analyze session variable assignment and increment

   The code sets $_SESSION['count'] to 1, then increments it by 1, making it 2.

2. Step 2: Output the session variable

   The echo statement prints the current value, which is 2.

3. Final Answer:

   2 -> Option A

4. Quick Check:

   1 incremented by 1 = 2 [OK]

Hint: Increment after setting 1 results in 2 [OK]

Common Mistakes:

• Assuming the value stays 1 without increment
• Thinking session variables reset each time
• Expecting an error without session_start()

4. Identify the error in this PHP code snippet:

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

medium

A. Cannot assign string to $_SESSION

B. Incorrect variable name, should be $SESSION

C. Missing session_start() before using $_SESSION

D. Echo statement syntax is wrong

Solution

1. Step 1: Check session initialization

   The code uses $_SESSION without calling session_start() first, which is required.

2. Step 2: Verify other options

   Variable name $_SESSION is correct, strings can be assigned, and echo syntax is valid.

3. Final Answer:

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

4. Quick Check:

   session_start() needed before $_SESSION = A [OK]

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

Common Mistakes:

• Forgetting session_start() causes undefined $_SESSION
• Confusing $_SESSION with $SESSION
• Thinking 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?

hard

A. <?php
$_SESSION['visits'] = 1;
echo $_SESSION['visits'];
?>

B. <?php
session_start();
if (!isset($_SESSION['visits'])) {
$_SESSION['visits'] = 1;
} else {
$_SESSION['visits']++;
}
echo "Visits: " . $_SESSION['visits'];
?>

C. <?php
session_start();
$_SESSION['visits']++;
echo $_SESSION['visits'];
?>

D. <?php
session_start();
$_SESSION['visits'] = 0;
echo $_SESSION['visits'];
?>

Solution

1. Step 1: Check session initialization and visit count logic

   <?php session_start(); if (!isset($_SESSION['visits'])) { $_SESSION['visits'] = 1; } else { $_SESSION['visits']++; } echo "Visits: " . $_SESSION['visits']; ?> starts the session, checks if 'visits' exists, initializes or increments it properly.

2. Step 2: Review other options for errors

   <?php $_SESSION['visits'] = 1; echo $_SESSION['visits']; ?> lacks session_start(), <?php session_start(); $_SESSION['visits']++; echo $_SESSION['visits']; ?> increments without initialization, <?php session_start(); $_SESSION['visits'] = 0; echo $_SESSION['visits']; ?> resets visits to 0 every time.

3. Final Answer:

   The code snippet that initializes visits=1 if not set, else increments -> Option B

4. Quick Check:

   Initialize then increment visits with session_start() = A [OK]

Hint: Initialize visits if not set, then increment [OK]

Common Mistakes:

• Not calling session_start() before $_SESSION
• Incrementing without checking if variable exists
• Resetting counter on every page load