Starting and using sessions in PHP - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this PHP session code?

Consider the following PHP code that uses sessions. What will be printed when this script runs?

PHP

<?php
session_start();
if (!isset($_SESSION['count'])) {
    $_SESSION['count'] = 1;
} else {
    $_SESSION['count']++;
}
echo $_SESSION['count'];
?>

A 1

B 0

C 2

D Undefined index error

💡 Hint

Think about what happens the first time the session variable is set.

The session variable 'count' is not set initially, so it is set to 1 and then printed. The output is 1.

❓ Predict Output

intermediate

What will this PHP code output after two page loads?

This PHP script uses sessions to count visits. What will it output on the second page load?

PHP

<?php
session_start();
if (!isset($_SESSION['visits'])) {
    $_SESSION['visits'] = 0;
}
$_SESSION['visits'] += 1;
echo $_SESSION['visits'];
?>

A 1

B 0

C Error: session not started

D 2

💡 Hint

Remember the session variable keeps its value between page loads.

On the first load, visits is set to 0 then incremented to 1. On the second load, it increments from 1 to 2, so output is 2.

🔧 Debug

advanced

Why does this PHP session code cause a warning?

Look at this PHP code snippet. It causes a warning about headers already sent. Why?

PHP

<?php
echo "Hello";
session_start();
$_SESSION['user'] = 'Alice';
?>

A The session variable 'user' is not initialized

B session_start() is deprecated after echo

C session_start() must be called before any output is sent

D You cannot set session variables after echo

💡 Hint

Think about when PHP sends HTTP headers.

session_start() sends HTTP headers. Headers must be sent before any output like echo. Here echo sends output first, causing the warning.

📝 Syntax

advanced

Which option correctly starts a session and sets a variable?

Choose the correct PHP code that starts a session and sets the session variable 'role' to 'admin'.

A

<?php
start_session();
$_SESSION['role'] = 'admin';
?>

B

<?php
session_start();
$_SESSION['role'] = 'admin';
?>

C

<?php
session_start;
$_SESSION['role'] = 'admin';
?>

D

<?php
session_start();
session['role'] = 'admin';
?>

💡 Hint

Check the function name and syntax carefully.

Only option B correctly calls session_start() as a function and uses $_SESSION superglobal properly.

🚀 Application

expert

What is the value of $_SESSION['total'] after this code runs?

Given this PHP code, what will be the value of $_SESSION['total'] after execution?

PHP

<?php
session_start();
if (!isset($_SESSION['total'])) {
    $_SESSION['total'] = 5;
}
function addToTotal($value) {
    $_SESSION['total'] += $value;
}
addToTotal(10);
addToTotal(-3);
?>

A 12

B 15

C 5

D Error: Undefined index 'total'

💡 Hint

Calculate the additions step by step.

Initially total is 5. Then addToTotal(10) makes it 15. Then addToTotal(-3) reduces it to 12.