$_SERVER information in PHP - Mini Project: Build & Apply

Exploring $_SERVER Information in PHP

📋 What You'll Learn

💡 Why This Matters

🌍 Real World

Web developers often need to check server environment details to debug or customize website behavior based on server or client information.

💼 Career

Understanding $_SERVER helps in backend web development, troubleshooting server issues, and writing dynamic PHP applications that respond to request details.

1

Create the initial $_SERVER keys list

Create a variable called keys_to_show and set it to an array with these exact strings: 'SERVER_NAME', 'SERVER_SOFTWARE', 'REQUEST_METHOD', 'SCRIPT_NAME', 'HTTP_USER_AGENT'.

PHP

# Create the array keys_to_show with the specified $_SERVER keys
# Your code here

Hint

Use square brackets [] to create an array with the exact keys listed.

2

Initialize the server_info array

Create an empty associative array called server_info to hold the selected $_SERVER information.

PHP

<?php
$keys_to_show = ['SERVER_NAME', 'SERVER_SOFTWARE', 'REQUEST_METHOD', 'SCRIPT_NAME', 'HTTP_USER_AGENT'];

# Create an empty array called server_info
# Your code here

Hint

Use = [] to create an empty array.

3

Fill server_info with selected $_SERVER data

Use a foreach loop with variable key to iterate over keys_to_show. Inside the loop, set server_info[key] to the value from $_SERVER[key] if it exists, or to the string 'Not set' if it does not.

PHP

<?php
$keys_to_show = ['SERVER_NAME', 'SERVER_SOFTWARE', 'REQUEST_METHOD', 'SCRIPT_NAME', 'HTTP_USER_AGENT'];

$server_info = [];

# Use foreach to fill server_info with $_SERVER values or 'Not set'
# Your code here

Hint

Use the null coalescing operator ?? to provide a default value if the $_SERVER key is missing.

4

Print the server_info contents

Use a foreach loop with variables key and value to iterate over server_info. Inside the loop, print each key and value in the format: key: value followed by a newline.

PHP

<?php
$keys_to_show = ['SERVER_NAME', 'SERVER_SOFTWARE', 'REQUEST_METHOD', 'SCRIPT_NAME', 'HTTP_USER_AGENT'];

$server_info = [];

foreach ($keys_to_show as $key) {
    $server_info[$key] = $_SERVER[$key] ?? 'Not set';
}

# Print each key and value from server_info
# Your code here

Hint

Use echo to print each key and value with a colon and newline.

Practice

1. What type of data does the PHP $_SERVER superglobal array hold?

easy

A. User input from forms

B. Information about headers, paths, and script locations

C. Database connection details

D. Session variables

Solution

1. Step 1: Understand what $_SERVER contains

   $_SERVER holds server and execution environment information like headers and script paths.

2. Step 2: Compare with other options

   User input is in $_POST or $_GET, database details are not stored here, and session variables are in $_SESSION.

3. Final Answer:

   Information about headers, paths, and script locations -> Option B

4. Quick Check:

   $_SERVER = server info [OK]

Hint: Remember: $_SERVER = server and request info [OK]

Common Mistakes:

• Confusing $_SERVER with $_POST or $_GET
• Thinking $_SERVER holds user session data
• Assuming $_SERVER contains database info

2. Which of the following is the correct way to get the current script's filename using $_SERVER?

easy

A. $_SERVER['SCRIPT_NAME']

B. $_SERVER['USER_AGENT']

C. $_SERVER['REMOTE_ADDR']

D. $_SERVER['HTTP_HOST']

Solution

1. Step 1: Identify the key for current script filename

   $_SERVER['SCRIPT_NAME'] returns the path of the current script.

2. Step 2: Understand other keys

   USER_AGENT is client browser info, REMOTE_ADDR is client IP, and HTTP_HOST is the host name.

3. Final Answer:

   $_SERVER['SCRIPT_NAME'] -> Option A

4. Quick Check:

   Script filename = $_SERVER['SCRIPT_NAME'] [OK]

Hint: SCRIPT_NAME gives current script path [OK]

Common Mistakes:

• Using REMOTE_ADDR for filename
• Confusing HTTP_HOST with script name
• Trying USER_AGENT for script info

3. What will the following PHP code output if the visitor's IP address is 192.168.1.10?

echo $_SERVER['REMOTE_ADDR'];

medium

A. 192.168.1.10

B. The server's IP address

C. The visitor's browser name

D. An empty string

Solution

1. Step 1: Understand what REMOTE_ADDR holds

   $_SERVER['REMOTE_ADDR'] contains the IP address of the client visiting the page.

2. Step 2: Match with given IP

   The visitor's IP is 192.168.1.10, so that is what will be printed.

3. Final Answer:

   192.168.1.10 -> Option A

4. Quick Check:

   REMOTE_ADDR = visitor IP [OK]

Hint: REMOTE_ADDR shows visitor IP address [OK]

Common Mistakes:

• Thinking REMOTE_ADDR is server IP
• Confusing REMOTE_ADDR with HTTP_USER_AGENT
• Expecting browser name instead of IP

4. Identify the error in this PHP code snippet that tries to print the visitor's browser info:

echo $_SERVER[HTTP_USER_AGENT];

medium

A. $_SERVER cannot be echoed directly

B. Using wrong key name

C. Missing quotes around the array key

D. HTTP_USER_AGENT is not available in $_SERVER

Solution

1. Step 1: Check array key syntax

   Array keys must be strings in quotes. Here, HTTP_USER_AGENT is missing quotes.

2. Step 2: Confirm key existence

   HTTP_USER_AGENT is a valid key in $_SERVER, so the key name is correct.

3. Final Answer:

   Missing quotes around the array key -> Option C

4. Quick Check:

   Array keys need quotes [OK]

Hint: Always quote $_SERVER keys like 'HTTP_USER_AGENT' [OK]

Common Mistakes:

• Forgetting quotes around keys
• Assuming key name is wrong
• Trying to echo whole $_SERVER array directly

5. You want to create a PHP script that shows the visitor's IP address and the current script's filename. Which code snippet correctly does this?

hard

A. echo 'IP: ' . $_SERVER['REMOTE_HOST'] . ', Script: ' . $_SERVER['SCRIPT_FILENAME'];

B. echo 'IP: ' . $_SERVER['SCRIPT_NAME'] . ', Script: ' . $_SERVER['REMOTE_ADDR'];

C. echo 'IP: ' . $_SERVER['HTTP_HOST'] . ', Script: ' . $_SERVER['REMOTE_ADDR'];

D. echo 'IP: ' . $_SERVER['REMOTE_ADDR'] . ', Script: ' . $_SERVER['SCRIPT_NAME'];

Solution

1. Step 1: Identify keys for IP and script filename

   REMOTE_ADDR is visitor IP, SCRIPT_NAME is current script path.

2. Step 2: Check code correctness

   echo 'IP: ' . $_SERVER['REMOTE_ADDR'] . ', Script: ' . $_SERVER['SCRIPT_NAME'];

   correctly concatenates IP and script name.

   echo 'IP: ' . $_SERVER['SCRIPT_NAME'] . ', Script: ' . $_SERVER['REMOTE_ADDR'];

   swaps them incorrectly.

   echo 'IP: ' . $_SERVER['HTTP_HOST'] . ', Script: ' . $_SERVER['REMOTE_ADDR'];

   uses HTTP_HOST (server host) instead of IP.

   echo 'IP: ' . $_SERVER['REMOTE_HOST'] . ', Script: ' . $_SERVER['SCRIPT_FILENAME'];

   uses REMOTE_HOST (often empty) and SCRIPT_FILENAME (full path, not filename).

3. Final Answer:

   echo 'IP: ' . $_SERVER['REMOTE_ADDR'] . ', Script: ' . $_SERVER['SCRIPT_NAME']; -> Option D

4. Quick Check:

   IP = REMOTE_ADDR, Script = SCRIPT_NAME [OK]

Hint: Use REMOTE_ADDR for IP and SCRIPT_NAME for script path [OK]

Common Mistakes:

• Mixing up REMOTE_ADDR and SCRIPT_NAME
• Using HTTP_HOST instead of REMOTE_ADDR
• Using REMOTE_HOST which may be empty