What is PHP

Introduction

PHP is a language that helps make websites work behind the scenes. It lets you create pages that can change and respond to what users do.

You want to build a website that shows different content to different users.

You need to save or get information from a database on a website.

You want to create forms that users can fill out and send data.

You want to make a website that can remember users when they come back.

You want to build a simple online store or blog.

Syntax

PHP

<?php
// PHP code goes here
?>

PHP code is written between <?php and ?> tags.

PHP runs on the server before the page is sent to the browser.

Examples

This prints 'Hello, world!' on the webpage.

PHP

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

This shows how to use a variable to print a name.

PHP

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

Sample Program

This program sets a name and prints a welcome message using PHP.

PHP

<?php
// Simple PHP program to greet a user
$user = "Friend";
echo "Welcome, $user!";
?>

Important Notes

PHP is mostly used for web development but can also be used for other tasks.

PHP code runs on the server, so users only see the result, not the code.

Summary

PHP helps make websites interactive and dynamic.

It runs on the server and sends results to the browser.

PHP code is written inside special tags and can print text or work with data.

Practice

1. What is PHP mainly used for?

easy

A. Designing static images

B. Editing videos

C. Writing desktop applications

D. Creating dynamic and interactive websites

Solution

1. Step 1: Understand PHP's purpose

   PHP is a language designed to create dynamic content on websites, making them interactive.

2. Step 2: Compare options

   Only Creating dynamic and interactive websites matches PHP's main use; others relate to different fields.

3. Final Answer:

   Creating dynamic and interactive websites -> Option D

4. Quick Check:

   PHP = Dynamic websites [OK]

Hint: PHP is for web interaction, not static or media tasks [OK]

Common Mistakes:

• Thinking PHP edits images or videos
• Confusing PHP with desktop app languages

2. Which of these is the correct way to start PHP code in a file?

easy

A. <?php

B. <script>

C. <php>

D. <?html>

Solution

1. Step 1: Recall PHP opening tags

   PHP code starts with <?php to tell the server to run PHP.

2. Step 2: Check other tags

   <script> is for JavaScript, <php> and <?html> are invalid.

3. Final Answer:

   <?php -> Option A

4. Quick Check:

   PHP code starts with <?php [OK]

Hint: PHP always starts with <?php tag [OK]

Common Mistakes:

• Using <script> instead of PHP tags
• Writing <php> which is not valid

3. What will this PHP code output?

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

medium

A. Syntax Error

B. Hello, World!

C. <?php echo "Hello, World!"; ?>

D. Nothing

Solution

1. Step 1: Understand echo statement

   The echo command prints the text inside quotes to the browser.

2. Step 2: Check code correctness

   The code is correct PHP syntax and will output the string exactly.

3. Final Answer:

   Hello, World! -> Option B

4. Quick Check:

   echo prints text = Hello, World! [OK]

Hint: echo prints text inside quotes [OK]

Common Mistakes:

• Expecting PHP code to show as text
• Thinking code causes error without semicolon

4. Find the error in this PHP code:

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

medium

A. Echo cannot print strings

B. Wrong opening PHP tag

C. Missing semicolon after echo statement

D. Quotes should be single quotes

Solution

1. Step 1: Check PHP syntax rules

   Each statement must end with a semicolon to separate commands.

2. Step 2: Identify missing semicolon

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

3. Final Answer:

   Missing semicolon after echo statement -> Option C

4. Quick Check:

   Statements end with ; = Missing semicolon [OK]

Hint: Every PHP statement ends with a semicolon [OK]

Common Mistakes:

• Ignoring semicolon at line end
• Thinking double quotes cause error

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

hard

A. <?php echo date('Y'); ?>

B. <?php print currentYear(); ?>

C. <?php echo 'year'; ?>

D. <?php showYear(); ?>

Solution

1. Step 1: Identify PHP function for current year

   The built-in function date('Y') returns the current year as a string.

2. Step 2: Check code snippets

   Only <?php echo date('Y'); ?> uses date('Y') correctly with echo to print the year.

3. Final Answer:

   <?php echo date('Y'); ?> -> Option A

4. Quick Check:

   date('Y') prints year = <?php echo date('Y'); ?> [OK]

Hint: Use date('Y') to get current year in PHP [OK]

Common Mistakes:

• Using undefined functions like currentYear()
• Printing literal strings instead of function output