PHP process model per request - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this PHP script?

Consider this PHP script executed on a web server for a single HTTP request:

<?php
$counter = 0;
function increment() {
    global $counter;
    $counter++;
    echo $counter . "\n";
}
increment();
increment();
?>

What will be printed when this script runs?

PHP

<?php
$counter = 0;
function increment() {
    global $counter;
    $counter++;
    echo $counter . "\n";
}
increment();
increment();
?>

A

1
2

B

2
4

C

1
1

D

0
1

💡 Hint

Remember that PHP variables do not keep their values between requests unless stored externally.

The variable $counter starts at 0 each time the script runs. The function increments it twice, printing 1 then 2.

🧠 Conceptual

intermediate

How does PHP handle variables between HTTP requests?

Which statement best describes how PHP manages variables across multiple HTTP requests?

A PHP keeps all variables in memory between requests for faster access.

B PHP automatically saves variables to a file after each request and reloads them on the next.

C PHP resets all variables at the start of each request; variables do not persist unless stored externally.

D PHP shares variables between requests using global shared memory by default.

💡 Hint

Think about what happens when you refresh a PHP page multiple times.

PHP runs each request in a new process or thread, so all variables are reset unless saved in sessions, databases, or files.

🔧 Debug

advanced

Why does this PHP script always print 1 on every request?

Look at this PHP code snippet:

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

Why does it always print 1 even after refreshing the page multiple times?

A Because the session is not started properly, so <code>$_SESSION</code> is empty every time.

B Because the code resets <code>$_SESSION['count']</code> to 1 in both the if and else blocks.

C Because the browser does not support cookies, so session ID is lost.

D Because PHP sessions do not persist data between requests.

💡 Hint

Check what happens inside the if and else blocks.

The code sets $_SESSION['count'] to 1 regardless of whether it existed before, so it never increments.

📝 Syntax

advanced

Which PHP code snippet correctly demonstrates per-request initialization?

Which of the following PHP code snippets correctly initializes a variable fresh for each HTTP request and then prints it?

A

<?php
$count++;
echo $count;
?>

B

<?php
static $count = 0;
$count++;
echo $count;
?>

C

<?php
global $count;
$count++;
echo $count;
?>

D

<?php
$count = 0;
$count++;
echo $count;
?>

💡 Hint

Remember that static variables keep their value during the script execution but are reset on new requests.

Option D initializes $count to 0 each request, then increments and prints 1. Option D causes a syntax error because static variables cannot be declared outside functions. Option D uses global without prior declaration. Option D increments an undefined variable causing a warning.

🚀 Application

expert

How to persist data across PHP requests without sessions?

You want to keep a counter that increases every time a PHP page is loaded, but you cannot use sessions. Which approach below will correctly persist the counter across requests?

A Store the counter in a text file and read/write it on each request.

B Use a static variable inside the PHP script to keep the counter value.

C Declare the counter as a global variable at the top of the script.

D Use a local variable inside a function and increment it.

💡 Hint

Think about where data can be saved outside the PHP process.

Static, global, or local variables reset on each request. Only external storage like files or databases can persist data across requests without sessions.