PHP

<?php
declare(strict_types=1);

echo "Hello, World!\n";

<ul>
<?php foreach ($users as $user): ?>
    <li><?= htmlspecialchars($user['name']) ?></li>
<?php endforeach; ?>
</ul>

$ php hello.php
$ php -S localhost:8000 -t public     # built-in dev server (not for production)
$ php -r 'echo PHP_VERSION, "\n";'
$ php -a                              # interactive shell

$name = "Alice";        // string
$age = 25;              // int
$height = 1.68;         // float
$isActive = true;       // bool
$nothing = null;        // null
$items = [1, 2, 3];     // array

$greeting = "Hello, $name!";             // interpolation in double quotes
$expr     = "Next year: {$age}y";        // braces for complex expressions
$raw      = 'No $interpolation here\n';  // single quotes: literal
$joined   = "Hello" . " " . "World";     // concatenation uses a dot

echo strlen($name), strtoupper($name), str_contains($name, "li");
echo sprintf("%s is %d years old", $name, $age);

$list = ["apple", "banana", "cherry"];
$list[] = "date";                                   // append

$user = ["name" => "Alice", "age" => 25];           // associative
echo $user["name"];
echo $user["email"] ?? "no email";                  // null coalescing: default when missing

[$first, $second] = $list;                          // destructuring
['name' => $n, 'age' => $a] = $user;

$squares = array_map(fn(int $x) => $x * $x, [1, 2, 3]);   // [1, 4, 9]
$even    = array_filter([1, 2, 3, 4], fn($x) => $x % 2 === 0);
$sum     = array_sum([1, 2, 3]);
sort($list);                                        // sorts in place
$merged  = [...$list, ...["extra"]];                // spread

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

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

for ($i = 0; $i < 3; $i++) { echo $i; }
while ($queue) { array_shift($queue); }

$label = match (true) {
    $age >= 65 => "Senior",
    $age >= 18 => "Adult",
    default    => "Minor",
};

function greet(string $name, string $greeting = "Hello"): string
{
    return "$greeting, $name!";
}

echo greet("Alice");
echo greet(greeting: "Hi", name: "Bob");   // named arguments (8.0+)

$tax = 0.15;
$withTax = function (float $price) use ($tax): float {
    return $price * (1 + $tax);
};

<?php
declare(strict_types=1);

interface Shape
{
    public function area(): float;
}

final class Circle implements Shape
{
    public function __construct(private float $radius) {}   // constructor promotion (8.0+)

    public function area(): float
    {
        return M_PI * $this->radius ** 2;
    }
}

$c = new Circle(2.0);
echo round($c->area(), 2);   // 12.57

enum Status: string
{
    case Draft = 'draft';
    case Published = 'published';

    public function label(): string
    {
        return ucfirst($this->value);
    }
}

$s = Status::from('draft');        // throws on an unknown value; tryFrom() returns null
echo $s->label();                  // Draft

trait Timestamps
{
    public ?string $createdAt = null;
    public function touch(): void { $this->createdAt = date('c'); }
}

class Post { use Timestamps; }

try {
    $result = intdiv(10, 0);
} catch (DivisionByZeroError $e) {
    error_log($e->getMessage());
} catch (InvalidArgumentException | TypeError $e) {
    // handle several types
} finally {
    echo "always runs";
}

throw new InvalidArgumentException("Age cannot be negative");

<?php
namespace App\Billing;

use App\Models\User;
use InvalidArgumentException;

final class Invoice { /* ... */ }

$ composer init
$ composer require guzzlehttp/guzzle        # add a dependency
$ composer require --dev phpunit/phpunit    # dev-only dependency
$ composer install                          # install exactly what composer.lock says
$ composer update                           # upgrade within the version constraints
$ composer dump-autoload                    # rebuild the class map

{
  "autoload": { "psr-4": { "App\\": "src/" } },
  "require": { "php": ">=8.2" }
}

require __DIR__ . '/vendor/autoload.php';   // once, in the entry point
$invoice = new App\Billing\Invoice();

<?php
// POST /login handled by a script
$email = trim($_POST['email'] ?? '');
$query = $_GET['page'] ?? 1;
$agent = $_SERVER['HTTP_USER_AGENT'] ?? '';

session_start();
$_SESSION['user_id'] = 42;

header('Content-Type: application/json');
echo json_encode(['ok' => true, 'user' => $email]);

$pdo = new PDO(
    'mysql:host=localhost;dbname=shop;charset=utf8mb4',
    $user,
    $pass,
    [
        PDO::ATTR_ERRMODE            => PDO::ERRMODE_EXCEPTION,
        PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
        PDO::ATTR_EMULATE_PREPARES   => false,
    ]
);

$stmt = $pdo->prepare('SELECT id, name FROM products WHERE price < :max AND active = :active');
$stmt->execute(['max' => 20, 'active' => 1]);
$products = $stmt->fetchAll();

// WRONG: injectable
$pdo->query("SELECT * FROM users WHERE email = '$email'");

// RIGHT
$stmt = $pdo->prepare('SELECT * FROM users WHERE email = ?');
$stmt->execute([$email]);

$ composer create-project laravel/laravel shop
$ cd shop && php artisan serve
$ php artisan make:model Product -m        # model plus migration
$ php artisan migrate
$ vendor/bin/phpunit
$ vendor/bin/phpstan analyse src --level=6

// Null and defaults
$v = $input ?? 'default';

// Array helpers
count($a); in_array($x, $a, true); array_keys($a); array_unique($a); usort($a, fn($x, $y) => $x <=> $y);

// Strings
trim($s); explode(',', $s); implode(',', $a); str_replace('a', 'b', $s); substr($s, 0, 5);

// Dates (prefer DateTimeImmutable)
$d = new DateTimeImmutable('2026-01-31');
echo $d->modify('+1 month')->format('Y-m-d');

// JSON
$data = json_decode($json, true, 512, JSON_THROW_ON_ERROR);
$json = json_encode($data, JSON_PRETTY_PRINT | JSON_THROW_ON_ERROR);

// Files
$text = file_get_contents('notes.txt');
file_put_contents('out.txt', $text, LOCK_EX);