How PHP executes on the server

Introduction

PHP runs on the server to create web pages before sending them to your browser. This helps make websites dynamic and interactive.

When you want to show different content to users based on their actions.

When you need to get data from a database and display it on a webpage.

When you want to process form information submitted by users.

When you want to create a login system that checks user credentials.

When you want to generate web pages quickly without making the user wait.

Syntax

PHP

<?php
// PHP code goes here
?>

PHP code is written inside tags.

The server reads and runs PHP code before sending the page to the browser.

Examples

This PHP code prints "Hello, world!" on the webpage.

PHP

<?php
echo "Hello, world!";
?>

This code sets a variable and prints a greeting using it.

PHP

<?php
$name = "Alice";
echo "Hello, $name!";
?>

Sample Program

This program sets a message and prints it. The server runs this code and sends the result to the browser.

PHP

<?php
// Simple PHP script to show how PHP runs on the server
$message = "Welcome to my website!";
echo $message;
?>

Important Notes

PHP code runs only on the server, so users never see the PHP code itself.

The server converts PHP code into plain HTML before sending it to the browser.

You need a web server with PHP installed to run PHP scripts.

Summary

PHP runs on the server to create dynamic web pages.

The server processes PHP code and sends only the result to the browser.

PHP helps make websites interactive and personalized.

Practice

1. What happens when a PHP file is requested by a browser?

easy

A. The PHP code is downloaded as a file to the browser

B. The browser runs the PHP code directly

C. The server runs the PHP code and sends the output to the browser

D. The server sends the PHP code as plain text to the browser

Solution

1. Step 1: Understand PHP execution location

   PHP code runs on the server, not in the browser.

2. Step 2: Identify what the browser receives

   The server sends only the output (usually HTML) to the browser, not the PHP code itself.

3. Final Answer:

   The server runs the PHP code and sends the output to the browser -> Option C

4. Quick Check:

   PHP runs on server = A [OK]

Hint: Remember: PHP runs on server, browser gets output only [OK]

Common Mistakes:

• Thinking browser executes PHP code
• Expecting PHP code to be visible in browser source
• Confusing PHP with client-side languages like JavaScript

2. Which of the following is the correct way to start a PHP block in a file?

easy

A.

B.

C.

D.

Solution

1. Step 1: Recall PHP opening tags

   The standard and recommended way to start PHP code is with

2. Step 2: Check each option

   uses which is correct. Others are invalid or incomplete tags.

3. Final Answer:

   -> Option A

4. Quick Check:

   Standard PHP tag = B [OK]

Hint: PHP code always starts with php [OK]

Common Mistakes:

• Using short tags like which may be disabled
• Confusing PHP tags with HTML or script tags
• Missing the 'php' keyword after

3. What will be the output of this PHP code when accessed via a browser?

<?php
echo "Hello, " . "world!";
?>

medium

A. Syntax Error

B. echo "Hello, " . "world!";

C. Hello, . world!

D. Hello, world!

Solution

1. Step 1: Understand echo statement

   The echo command outputs the combined string "Hello, world!" to the browser.

2. Step 2: Confirm string concatenation

   The dot operator joins "Hello, " and "world!" correctly without errors.

3. Final Answer:

   Hello, world! -> Option D

4. Quick Check:

   echo concatenates strings = D [OK]

Hint: echo prints combined strings directly [OK]

Common Mistakes:

• Expecting PHP code to show in browser
• Confusing concatenation operator
• Thinking dot prints as text

4. Identify the error in this PHP code snippet:

<?php
echo "Welcome to PHP!"
?>

medium

A. Missing quotes around string

B. Missing semicolon after echo statement

C. Incorrect PHP opening tag

D. Using echo instead of print

Solution

1. Step 1: Check syntax of echo statement

   PHP statements must end with a semicolon ; to separate commands.

2. Step 2: Locate missing semicolon

   The echo line lacks a semicolon at the end, causing a syntax error.

3. Final Answer:

   Missing semicolon after echo statement -> Option B

4. Quick Check:

   Statements need ; = C [OK]

Hint: Always end PHP statements with a semicolon ; [OK]

Common Mistakes:

• Forgetting semicolon at line end
• Confusing PHP tags with HTML tags
• Assuming echo doesn't need semicolon

5. You want to create a PHP page that shows the current year dynamically. Which code snippet correctly does this?

<?php
// Options:
// A: echo date("Y");
// B: echo "date(Y)";
// C: echo date(Y, Y);
// D: echo "Y";
?>

hard

A. echo date("Y");

B. echo "date(Y)";

C. echo date(Y, Y);

D. echo "Y";

Solution

1. Step 1: Understand PHP date function usage

   The date function requires the format string in quotes to return the current year.

2. Step 2: Evaluate each option

   echo date("Y"); correctly calls date("Y") to output the year. echo "date(Y)"; prints the string literally. echo date(Y, Y); misses quotes causing undefined constants and wrong output (1970). echo "Y"; prints letter Y only.

3. Final Answer:

   echo date("Y"); -> Option A

4. Quick Check:

   Correct date format string = A [OK]

Hint: Use quotes around format in date() function [OK]

Common Mistakes:

• Omitting quotes around format string
• Printing function call as string
• Confusing output with literal text