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Summary of PHP Documentation

Overview

PHP (Hypertext Preprocessor) is a widely-used, open-source, server-side scripting language designed for web development. It is also a general-purpose language that can be embedded into HTML.

Key Features

  • Dynamic Web Content: Generates HTML dynamically on the server.
  • Database Integration: Built-in support for databases like MySQL, PostgreSQL, and SQLite.
  • Cross-Platform: Runs on various operating systems (Linux, Windows, macOS).
  • Extensive Library Support: Standard libraries and third-party frameworks enhance functionality.
  • Ease of Integration: Embeds directly into HTML and integrates with various web technologies.

Core Concepts

Syntax Basics

  • PHP Tags: 
    <?php
echo "Hello, PHP!";
?>
  • Comments: 
    // Single-line comment
# Another single-line comment
/* Multi-line
   comment */

Variables

  • Declared with a $ prefix and no explicit type declaration (dynamic typing). 
    $name = "PHP";
$version = 8.0;
$isActive = true;

Data Types

  • Primitive: string, integer, float, boolean
  • Compound: array, object, callable, iterable
  • Special: NULL, resource

Operators

  • Arithmetic: +, -, *, /, %
  • String: . (concatenation)
  • Comparison: ==, ===, !=, !==, <, >, <=, >=
  • Logical: &&, ||, !
  • Assignment: =, +=, -=, .=

Control Structures

Conditionals

if ($age > 18) {
    echo "Adult";
} elseif ($age > 12) {
    echo "Teenager";
} else {
    echo "Child";
}

Loops

  • For Loop: 
    for ($i = 0; $i < 10; $i++) {
    echo $i;
}
  • While Loop: 
    while ($count < 5) {
    echo $count++;
}
  • Foreach Loop: 
    foreach ($array as $key => $value) {
    echo "$key: $value";
}

Functions

  • Definition: 
    function greet($name) {
    return "Hello, $name!";
}
echo greet("PHP");
  • Default Parameters: 
    function greet($name = "Guest") {
    return "Hello, $name!";
}

Arrays

  • Indexed Arrays: 
    $colors = ["red", "green", "blue"];
echo $colors[0]; // Outputs: red
  • Associative Arrays: 
    $ages = ["Alice" => 25, "Bob" => 30];
echo $ages["Alice"]; // Outputs: 25

Object-Oriented Programming (OOP)

  • Class and Object:

    class Car {
    public $brand;
    public function __construct($brand) {
        $this->brand = $brand;
    }
    public function honk() {
        return "Honk! I am a $this->brand.";
    }
}
$car = new Car("Toyota");
echo $car->honk();

  • Inheritance:

    class ElectricCar extends Car {
    public $batteryLife;
    public function charge() {
        return "Charging the battery.";
    }
}

File Handling

  • Reading a File: 
    $content = file_get_contents("example.txt");
echo $content;
  • Writing to a File: 
    file_put_contents("example.txt", "Hello, PHP!");

Database Interaction

  • Using PDO (PHP Data Objects): 
    try {
    $pdo = new PDO("mysql:host=localhost;dbname=testdb", "username", "password");
    $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    $stmt = $pdo->query("SELECT * FROM users");
    foreach ($stmt as $row) {
        print_r($row);
    }
} catch (PDOException $e) {
    echo "Connection failed: " . $e->getMessage();
}

Error Handling

  • Use try, catch, and finally for exception handling: 
    try {
    if (!file_exists("example.txt")) {
        throw new Exception("File not found");
    }
} catch (Exception $e) {
    echo $e->getMessage();
}

Best Practices

  • Use strict types when possible: 
    declare(strict_types=1);
  • Enable error reporting during development: 
    error_reporting(E_ALL);
ini_set('display_errors', 1);
  • Sanitize user input to prevent security vulnerabilities (e.g., SQL injection, XSS).
  • Use prepared statements for database queries.

Resources

PHP is a versatile language, especially suited for web development, with a rich ecosystem of tools and frameworks like Laravel, Symfony, and WordPress.