Variables
PHP variables start with a $ sign and are dynamically typed.
<?php
$name = "Alice";
$age = 30;
$price = 19.99;
?>Arrays
Arrays can be indexed or associative.
<?php
// Indexed array
$colors = ["red", "green", "blue"];
// Associative array
$user = ["name" => "Alice", "age" => 30];
?>Functions
Functions encapsulate reusable logic.
<?php
function greet($name) {
return "Hello, $name!";
}
echo greet("Alice");
?>Object-Oriented Programming
PHP supports classes, objects, inheritance, and interfaces.
<?php
class User {
public $name;
public function __construct($name) {
$this->name = $name;
}
public function greet() {
return "Hello, $this->name!";
}
}
$user = new User("Alice");
echo $user->greet();
?>Superglobals
Special global arrays like $_GET, $_POST, $_SESSION, $_COOKIE, $_SERVER provide access to request and environment data.
<?php
$name = $_GET['name'] ?? 'Guest';
echo "Hello, $name!";
?>Sessions & Cookies
Sessions and cookies are used to persist user data across requests.
<?php
// Start session
session_start();
$_SESSION['user'] = 'Alice';
// Set cookie
setcookie('theme', 'dark', time()+3600);
?>File Handling
PHP can read, write, and manipulate files easily.
<?php
// Write to a file
file_put_contents('example.txt', "Hello World");
// Read from a file
$content = file_get_contents('example.txt');
echo $content;
?>Error & Exception Handling
Use try, catch, and finally for robust error handling.
<?php
try {
throw new Exception("Something went wrong!");
} catch (Exception $e) {
echo $e->getMessage();
} finally {
// Always runs
}
?>Form Handling & Validation
Process and validate user input from forms.
<?php
if ($_SERVER['REQUEST_METHOD'] === 'POST') {
$email = filter_input(INPUT_POST, 'email', FILTER_VALIDATE_EMAIL);
if ($email) {
echo "Valid email: $email";
} else {
echo "Invalid email.";
}
}
?>Regular Expressions
Use preg_match and preg_replace for pattern matching.
<?php
$text = "My phone: 123-456-7890";
if (preg_match('/\d{3}-\d{3}-\d{4}/', $text, $matches)) {
echo "Found: " . $matches[0];
}
?>Date & Time Functions
Work with dates and times using built-in functions.
<?php
echo date('Y-m-d H:i:s');
$now = new DateTime();
echo $now->format('l, F j, Y');
?>HTTP Requests (cURL)
Use cURL to make HTTP requests to other servers.
<?php
$ch = curl_init('https://api.example.com/data');
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$response = curl_exec($ch);
curl_close($ch);
echo $response;
?>JSON Encoding/Decoding
Convert data to and from JSON format.
<?php
$data = ['name' => 'Alice', 'age' => 30];
$json = json_encode($data);
$decoded = json_decode($json, true);
?>Autoloading & PSR Standards
Use autoloading for classes and follow PSR standards for interoperability.
<?php
spl_autoload_register(function ($class) {
include $class . '.php';
});
?>Environment Variables & Configuration
Store sensitive data in environment variables and config files.
<?php
$db_host = getenv('DB_HOST');
?>PHP 8 Features
- Attributes (annotations)
- Union types
- Match expression
- Constructor property promotion
- Named arguments
<?php
// Match expression
$result = match($status) {
'success' => '✅',
'error' => '❌',
default => '⏳',
};
?>Security Best Practices
- Validate and sanitize user input
- Use prepared statements for SQL queries
- Escape output to prevent XSS
- Use password hashing (
password_hash) - Keep PHP and dependencies updated
Design Patterns in PHP
Common patterns like Singleton, Factory, and Observer help organize code.
<?php
class Singleton {
private static $instance;
private function __construct() {}
public static function getInstance() {
if (!self::$instance) {
self::$instance = new Singleton();
}
return self::$instance;
}
}
?>Dependency Injection
Pass dependencies to objects for flexibility and testability.
<?php
class Logger {}
class UserService {
private $logger;
public function __construct(Logger $logger) {
$this->logger = $logger;
}
}
?>RESTful APIs with PHP
Build APIs using PHP and handle JSON requests/responses.
<?php
header('Content-Type: application/json');
$data = ['status' => 'success'];
echo json_encode($data);
?>Testing (PHPUnit)
Write unit tests for PHP code using PHPUnit.
// Example PHPUnit test
class UserTest extends \PHPUnit\Framework\TestCase {
public function testGreet() {
$user = new User('Alice');
$this->assertEquals('Hello, Alice!', $user->greet());
}
}
Working with Databases
Use PDO or MySQLi for secure database access.
<?php
$pdo = new PDO('mysql:host=localhost;dbname=test', 'user', 'pass');
$stmt = $pdo->prepare('SELECT * FROM users');
$stmt->execute();
$users = $stmt->fetchAll();
?>Frameworks (Laravel, Symfony)
Popular frameworks provide structure and features for rapid development.
- Laravel: Eloquent ORM, routing, Blade templates
- Symfony: Components, bundles, robust architecture
Internationalization (i18n)
Support multiple languages using gettext or custom solutions.
<?php
putenv('LC_ALL=en_US');
setlocale(LC_ALL, 'en_US');
bindtextdomain('messages', './locale');
textdomain('messages');
echo gettext('Hello');
?>Performance Optimization
- Use opcode caching (OPcache)
- Profile code with Xdebug
- Optimize database queries
- Minimize I/O operations
Working with XML
Parse and generate XML using SimpleXML or DOMDocument.
<?php
$xml = simplexml_load_string('Alice CLI Scripts in PHP
Write command-line scripts for automation and maintenance.
<?php
if (php_sapi_name() === 'cli') {
echo "Running from CLI";
}
?>Advanced Concepts
- Namespaces
- Traits
- Type declarations
- Error handling (
try/catch) - Composer for dependency management