🐘 PHP (Hypertext Preprocessor)

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📌 1. Definition

PHP is a server-side scripting language used to create dynamic and interactive web pages. It runs on the web server and sends processed output (HTML) to the browser.

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🌐 2. How PHP Works (Diagram Description)

👉 Draw this in exam:

Browser → Request → Web Server (PHP Code)
                 ↓
           Process Logic
                 ↓
          Send HTML Response → Browser

✔ PHP code is executed on server, not visible to user.

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🧱 3. Basic PHP Syntax

<?php
echo "Hello World";
?>

🔑 Key Points

• PHP code starts with <?php and ends with ?>
• Each statement ends with ;
• echo is used to display output

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🧠 4. Variables in PHP

📌 Definition

Variables store data values.

<?php
$name = "Ali";
$age = 20;
?>

⭐ Rules

• Starts with $
• Case-sensitive
• No need to declare data type

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🔢 5. Data Types

• String
• Integer
• Float
• Boolean
• Array
• Object
• NULL

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➕ 6. Operators

• Arithmetic: + - * / %
• Assignment: =
• Comparison: == != > <
• Logical: && || !

<?php
$x = 10 + 5;
?>

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🔀 7. Control Statements

1. If-Else

<?php
if ($x > 10) {
  echo "Greater";
} else {
  echo "Smaller";
}
?>

2. Loops

<?php
for ($i = 0; $i < 5; $i++) {
  echo $i;
}
?>

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🔧 8. Functions

<?php
function greet() {
  echo "Hello!";
}
greet();
?>

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🌍 9. Forms Handling (Important)

HTML Form

<form method="post">
  Name: <input type="text" name="name">
  <input type="submit">
</form>

PHP Processing

<?php
$name = $_POST['name'];
echo $name;
?>

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🗄️ 10. Working with Database (MySQL)

<?php
$conn = mysqli_connect("localhost", "root", "", "test");
?>

🔑 Steps

1. Connect database
2. Execute query
3. Fetch data

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📂 11. Superglobals (Important)

• $_GET
• $_POST
• $_SERVER
• $_SESSION
• $_COOKIE

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🔐 12. Sessions & Cookies

Session Example

<?php
session_start();
$_SESSION["user"] = "Ali";
?>

Cookie Example

<?php
setcookie("user", "Ali", time()+3600);
?>

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📊 13. PHP Execution Flow

User Request → Server → PHP Execution → Database → Response (HTML)

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⚠️ 14. Important Rules

✔ PHP runs on server-side ✔ File extension is .php ✔ Can be embedded in HTML ✔ Use $_POST for secure data transfer ✔ Always validate user input

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📈 15. Advantages

• Open-source
• Easy to learn
• Database support
• Platform-independent
• Fast execution

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❌ 16. Limitations

• Less secure if not coded properly
• Slower than some modern frameworks
• Mixing HTML & PHP can reduce readability

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❓ 17. Likely Exam Questions

Short Questions

1. Define PHP.
2. What are PHP variables?
3. List PHP data types.
4. What are superglobals?
5. What is session?

Long Questions

6. Explain PHP syntax with example.
7. Describe form handling in PHP.
8. Explain PHP with database connectivity.
9. Discuss sessions and cookies.
10. Compare PHP with JavaScript.

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📝 18. Summary / Quick Revision

• PHP = Server-side language

• Used for:

  • Dynamic pages
  • Form handling
  • Database interaction

• Key features:

  • Variables ($)
  • Superglobals
  • Sessions & Cookies

👉 Works with HTML + CSS + JavaScript to build full web applications.

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