Comparison with long-running servers (Node.js) in PHP - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to print a message in PHP.

PHP

<?php
 echo [1];
?>

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

A"Hello, world!"

Bprint("Hello, world!")

CHello, world!

Decho Hello, world!

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting quotes around the string

Using print() inside echo

In PHP, strings must be enclosed in quotes when using echo.

2fill in blank

medium

Complete the code to start a PHP built-in server on port 8000.

PHP

php -S [1]

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

A127.0.0.1:9000

Blocalhost:8080

C0.0.0.0:8000

Dlocalhost:8000

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong port number

Using IP instead of localhost

The built-in PHP server commonly runs on localhost:8000 by default.

3fill in blank

hard

Fix the error in the PHP code that tries to keep a long-running server alive.

PHP

<?php
while (true) {
    [1]("Server running...\n");
    sleep(5);
}
?>

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

Aprint

Becho

Cconsole.log

Dprintf

Attempts:

3 left

💡 Hint

Common Mistakes

Using JavaScript functions like console.log

Using print without parentheses

In PHP, echo is used to output text. console.log is JavaScript and will cause an error.

4fill in blank

hard

Fill both blanks to create a PHP script that listens on port 8080 and outputs a response.

PHP

<?php
$address = '127.0.0.1';
$port = [1];
$socket = socket_create(AF_INET, SOCK_STREAM, SOL_TCP);
socket_bind($socket, $address, $port);
socket_listen($socket);

$client = socket_accept($socket);
socket_write($client, [2]);
socket_close($client);
socket_close($socket);
?>

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

A8080

B"Hello from PHP server!"

C80

D"Welcome!"

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong port number

Not quoting the message string

Port 8080 is commonly used for testing servers. The message must be a string in quotes.

5fill in blank

hard

Fill all three blanks to create a PHP script that accepts a connection, reads data, and sends a response.

PHP

<?php
$address = '0.0.0.0';
$port = [1];
$socket = socket_create(AF_INET, SOCK_STREAM, SOL_TCP);
socket_bind($socket, $address, $port);
socket_listen($socket);

$client = socket_accept($socket);
$data = socket_read($client, [2]);
socket_write($client, [3]);
socket_close($client);
socket_close($socket);
?>

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

A9000

B1024

C"Data received"

D512

Attempts:

3 left

💡 Hint

Common Mistakes

Using too small or too large read size

Not quoting the response string

Port 9000 is a common test port. Reading 1024 bytes is typical. The response must be a quoted string.

Practice

1. Which statement best describes how PHP handles variables compared to Node.js in a web server context?

easy

A. PHP keeps variables in memory between requests, but Node.js resets them every time.

B. Both PHP and Node.js reset variables on every request.

C. PHP resets variables on every request, while Node.js keeps variables in memory between requests.

D. Both PHP and Node.js keep variables in memory between requests.

Solution

1. Step 1: Understand PHP's request model

   PHP scripts start fresh on each request, so all variables are reset.

2. Step 2: Understand Node.js server behavior

   Node.js servers run continuously, so variables can persist in memory across requests.

3. Final Answer:

   PHP resets variables on every request, while Node.js keeps variables in memory between requests. -> Option C

4. Quick Check:

   PHP resets, Node.js persists [OK]

Hint: Remember PHP restarts each request; Node.js runs continuously [OK]

Common Mistakes:

• Thinking PHP keeps variables in memory between requests
• Assuming Node.js resets variables like PHP
• Confusing session storage with variable persistence

2. Which of the following PHP code snippets correctly starts a session to preserve data across requests?

easy

A.

B.

C.

D.

Solution

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

   The correct function is session_start() to begin or resume a session.

2. Step 2: Check the code syntax

   uses session_start() correctly; others use invalid function names.

3. Final Answer:

   <?php session_start(); $_SESSION['count'] = 1; ?> -> Option A

4. Quick Check:

   Use session_start() to begin sessions [OK]

Hint: Use session_start() exactly to enable sessions [OK]

Common Mistakes:

• Using incorrect function names like start_session()
• Forgetting to call session_start() before using $_SESSION
• Assuming sessions start automatically

3. Consider this PHP code snippet run on two separate requests:

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

What will be the output on the second request?

medium

A. 1

B. 2

C. 0

D. Error

Solution

1. Step 1: Analyze session variable initialization

   On the first request, $_SESSION['visits'] is not set, so it is initialized to 1.

2. Step 2: Analyze second request behavior

   On the second request, $_SESSION['visits'] exists, so it increments by 1, becoming 2.

3. Final Answer:

   2 -> Option B

4. Quick Check:

   Session increments visits count correctly [OK]

Hint: Sessions keep data; visits count increases each request [OK]

Common Mistakes:

• Assuming visits resets to 1 every request
• Forgetting to call session_start()
• Expecting an error due to undefined index

4. This PHP script is intended to count visits using sessions, but it always outputs 1 on every request:

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

What is the most likely cause of this problem?

medium

A. The session_start() function is missing, so sessions don't work.

B. The $_SESSION variable is overwritten elsewhere in the code.

C. The $_SESSION['count'] variable is reset manually each time.

D. The echo statement is inside the else block only.

Solution

1. Step 1: Check for session initialization

   The code does not call session_start(), so PHP does not load or save session data.

2. Step 2: Understand session behavior without session_start()

   Without starting the session, $_SESSION is empty each request, so count resets to 1 every time.

3. Final Answer:

   The session_start() function is missing, so sessions don't work. -> Option A

4. Quick Check:

   Always call session_start() before using $_SESSION [OK]

Hint: Always start session with session_start() to keep data [OK]

Common Mistakes:

• Assuming $_SESSION works without session_start()
• Thinking variable reset is due to manual code
• Ignoring session initialization step

5. You want to simulate a long-running server behavior in PHP to keep a counter in memory across multiple requests without using sessions or databases. Which approach is the best to achieve this?

hard

A. Restart the PHP server after each request to reset variables.

B. Store the counter in a local variable inside a PHP script executed per request.

C. Use cookies to store the counter on the client side only.

D. Use a PHP daemon script running continuously and communicate via sockets or shared memory.

Solution

1. Step 1: Understand PHP's request lifecycle

   PHP scripts run fresh on each request, so local variables reset automatically.

2. Step 2: Identify how to keep data in memory across requests

   To keep data in memory like Node.js, PHP must run as a long-running process (daemon) and communicate externally.

3. Step 3: Evaluate options

   Use a PHP daemon script running continuously and communicate via sockets or shared memory. describes running a PHP daemon with sockets/shared memory, which simulates long-running server behavior.

4. Final Answer:

   Use a PHP daemon script running continuously and communicate via sockets or shared memory. -> Option D

5. Quick Check:

   Long-running PHP needs daemon + IPC, not per-request scripts [OK]

Hint: Run PHP as daemon with IPC to keep data in memory [OK]

Common Mistakes:

• Thinking local variables persist across requests
• Confusing cookies with server memory
• Restarting server resets all variables