PHP

TL;DR

One-liner: PHP powers 70%+ of the web - it’s not sexy, but it works.

Core Strengths:

• Easy to learn, easy to deploy
• Powers WordPress, Laravel, Drupal
• Available on virtually every web host
• Mature ecosystem with Composer

Philosophy

PHP was built for the web:

• Pragmatic over pure - It evolved to solve real problems, not to be academically elegant
• Low barrier to entry - Mix PHP and HTML, echo a variable, refresh browser, done
• Batteries included - Database, JSON, XML, file handling all built-in
• Forgiving - Type coercion, default values, it tries to make things work

Modern PHP (8.x) has evolved significantly - types, attributes, match expressions, named arguments. It’s not your grandpa’s PHP anymore.

Quick Start

Install

# macOS
brew install php

# Linux (Ubuntu)
sudo apt install php php-cli

# Windows - download from windows.php.net

Verify (latest: 8.5)

php --version  # PHP 8.5.1

First Program

Create hello.php:

<?php
echo "Hello, World!\n";

php hello.php

Built-in Web Server

php -S localhost:8000
# Open http://localhost:8000 in browser

Interactive Mode

php -a
php > echo 2 + 2;
4

Language Essentials

Variables & Types

// Variables start with $
$name = "Alice";
$age = 25;
$price = 19.99;
$active = true;

// Arrays (both indexed and associative)
$numbers = [1, 2, 3];
$user = ["name" => "Alice", "age" => 25];

// Type declarations (PHP 7+)
function greet(string $name): string {
    return "Hello, $name!";
}

Control Flow

// if-else
if ($age >= 18) {
    echo "Adult";
} elseif ($age >= 13) {
    echo "Teen";
} else {
    echo "Child";
}

// Match expression (PHP 8+)
$status = match($code) {
    200 => "OK",
    404 => "Not Found",
    500 => "Error",
    default => "Unknown"
};

// foreach
foreach ($users as $user) {
    echo $user["name"];
}

foreach ($user as $key => $value) {
    echo "$key: $value";
}

Functions

// Basic function
function greet($name) {
    return "Hello, $name!";
}

// Default parameters
function greet($name, $greeting = "Hello") {
    return "$greeting, $name!";
}

// Named arguments (PHP 8+)
greet(greeting: "Hi", name: "Alice");

// Arrow functions
$double = fn($x) => $x * 2;

Classes

class User {
    public function __construct(
        public string $name,
        public int $age,
        public bool $admin = false
    ) {}

    public function isAdult(): bool {
        return $this->age >= 18;
    }
}

$user = new User("Alice", 25);
echo $user->name;       // Alice
echo $user->isAdult();  // true

Error Handling

// Try-catch
try {
    $result = riskyOperation();
} catch (Exception $e) {
    echo "Error: " . $e->getMessage();
} finally {
    cleanup();
}

// Null safe operator (PHP 8+)
$name = $user?->profile?->name;

// Null coalescing
$name = $user["name"] ?? "Guest";

Gotchas

== vs ===

0 == "hello"   // true! (type juggling)
0 === "hello"  // false (strict comparison)

// Always use === for comparisons
if ($value === false) {
    // Only matches actual false, not 0, "", or null
}

Variable scope in functions

$x = 10;

function test() {
    // $x is not accessible here!
    global $x;  // Now it is
    echo $x;
}

// Or use closures
$fn = function() use ($x) {
    echo $x;
};

Arrays are passed by value

$arr1 = [1, 2, 3];
$arr2 = $arr1;      // Copy!
$arr2[] = 4;        // Only $arr2 has 4

// Pass by reference
function addItem(&$arr, $item) {
    $arr[] = $item;  // Modifies original
}

Falsy values are everywhere

// All of these are falsy
false, 0, 0.0, "", "0", [], null

// Check for null specifically
if ($value === null) { }

// Check if set and not empty
if (!empty($value)) { }

When to Choose

Best for:

• Content sites (WordPress, Drupal)
• Web applications (Laravel, Symfony)
• APIs (PHP 8+ with typed properties)
• Shared hosting environments

Not ideal for:

• CLI tools (use Go, Rust)
• Real-time applications (use Node.js)
• Data science (use Python)

Comparison:

Aspect	PHP	Python	Node.js
Web focus	Native	Django/Flask	Express
Speed	Fast (8.x)	Medium	Fast
Hosting	Everywhere	Limited	VPS
Learning	Easy	Easy	Medium

Next Steps

• PHP Manual
• Laravel
• PHP The Right Way
• Composer

Ecosystem

Package Management

# Composer (the standard)
composer init              # Create project
composer require pkg/name  # Add package
composer install           # Install dependencies
composer update            # Update dependencies

Popular Packages

• Web: Laravel, Symfony, Slim
• CMS: WordPress, Drupal
• Testing: PHPUnit, Pest
• ORM: Eloquent, Doctrine