Setting and reading cookies in PHP - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this PHP code that sets and reads a cookie?

Consider the following PHP code snippet that sets a cookie and then tries to read it immediately. What will be the output?

PHP

<?php
setcookie('user', 'Alice', time() + 3600);
if (isset($_COOKIE['user'])) {
    echo $_COOKIE['user'];
} else {
    echo 'No cookie found';
}
?>

A Alice

B Empty string

C Undefined index error

D No cookie found

💡 Hint

Remember that cookies set by setcookie() are not available until the next page load.

The setcookie() function sends a cookie header to the browser, but the $_COOKIE superglobal is not updated until the next request. So immediately after setting, $_COOKIE['user'] is not set, resulting in 'No cookie found'.

🧠 Conceptual

intermediate

Which PHP function is used to set a cookie?

In PHP, which function is used to send a cookie to the browser?

A cookie_set()

B sendcookie()

C setcookie()

D createcookie()

💡 Hint

The function name starts with 'set'.

The correct function to set a cookie in PHP is setcookie(). Other options are invalid function names.

❓ Predict Output

advanced

What will be the output of this PHP code reading a cookie?

Given the following PHP code, what will be the output if the cookie 'session' is set to 'xyz123'?

PHP

<?php
if (!empty($_COOKIE['session'])) {
    echo 'Session ID: ' . $_COOKIE['session'];
} else {
    echo 'No session cookie';
}
?>

A Session ID: xyz123

B No session cookie

C Undefined index: session

D Session ID:

💡 Hint

Check if the cookie exists and is not empty.

If the cookie 'session' is set to 'xyz123', the condition !empty($_COOKIE['session']) is true, so it prints 'Session ID: xyz123'.

🔧 Debug

advanced

Why does this PHP code fail to delete a cookie?

Examine the code below. It tries to delete a cookie named 'theme' but fails. What is the reason?

PHP

<?php
setcookie('theme', '', time() + 3600);
if (!isset($_COOKIE['theme'])) {
    echo 'Cookie deleted';
} else {
    echo 'Cookie still exists';
}
?>

A setcookie() cannot delete cookies

B The expiration time should be in the past to delete a cookie

C Cookie name is incorrect

D Cookie value cannot be empty

💡 Hint

To delete a cookie, you must expire it immediately.

To delete a cookie, you must set its expiration time to a past time. Setting it to time() + 3600 sets it to expire in the future, so it remains.

🚀 Application

expert

How many cookies will be sent to the browser after this PHP script runs?

Consider this PHP script that sets multiple cookies. How many cookies will the browser receive?

PHP

<?php
setcookie('a', '1', time() + 3600);
setcookie('b', '2', time() + 3600, '/path1');
setcookie('c', '3', time() + 3600, '/path2');
setcookie('a', '4', time() + 3600, '/path1');
?>

A 4

B 1

C 2

D 3

💡 Hint

Cookies with the same name but different paths are treated as separate cookies.

The script issues four setcookie() calls, each producing a distinct Set-Cookie header. The two 'a' cookies differ by path (default '/' vs '/path1'), making all four unique: 'a' (path '/'), 'b' (path '/path1'), 'c' (path '/path2'), 'a' (path '/path1'). Thus, 4 cookies are sent.