<?php
 echo 'Hello World';
?>

// single line
# also single line
/* multi
 line */

echo 'Hello', ' ', 'World';
print('Hello World');

$name = 'John';
$age = 25;

$name='Tom';
echo "Hi $name"; // Hi Tom
echo 'Hi $name'; // Hi $name

$full = 'Hello' . ' ' . 'World';

define('SITE_NAME', 'MyApp');
const PI = 3.14;

if (isset($name)) { echo 'set'; }

unset($name);

include 'header.php';

echo phpversion();

$status = ($age >= 18) ? 'Adult' : 'Minor';

var_dump(gettype(5)); // 'integer'

var_dump(0 == 'a'); // false in PHP8, true in PHP7
var_dump(1 === '1'); // false

var_dump([1, 'two', 3.0]);

$user = ['name' => 'Alice', 'age' => 30];

$matrix = [[1,2],[3,4]];

$n = (int) '42'; $f = floatval('3.14');

echo 10 % 3; // 1

do { echo $i; $i++; } while ($i < 5);

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

switch($day){
 case 1: echo 'Mon'; break;
 default: echo 'Other';
}

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

function greet($name = 'Guest') { echo $name; }

$fruits = array('apple', 'banana');
$fruits2 = ['apple', 'banana'];

$arr[] = 'new item';
array_push($arr, 'new item');

$last = array_pop($arr);

$first = array_shift($arr);

array_unshift($arr, 'first');

if (in_array('apple', $fruits)) { echo 'found'; }

if (array_key_exists('name', $user)) { echo 'yes'; }

echo count($arr);

$part = array_slice($arr, 1, 2);

$unique = array_unique([1,2,2,3]);

$reversed = array_reverse([1,2,3]);

echo strlen('Hello'); // 5

$pos = strpos('Hello World', 'World'); // 6

echo str_replace('World', 'PHP', 'Hello World');

echo substr('Hello World', 0, 5); // 'Hello'

$parts = explode(',', 'a,b,c'); // ['a','b','c']

echo implode(', ', ['a','b','c']); // 'a, b, c'

echo number_format(1234567.891, 2); // '1,234,567.89'

echo str_repeat('ab', 3); // 'ababab'

echo strrev('hello'); // 'olleh'

class Car {
 public string $model;
 function drive() { echo 'Driving'; }
}

$car = new Car();

class User {
 public function __construct(public string $name) {}
}

class Animal { function eat(){} }
class Dog extends Animal {}

class Circle { const PI = 3.14159; }

if ($car instanceof Vehicle) { echo 'yes'; }

try {
 $result = 10 / $divisor;
} catch (DivisionByZeroError $e) {
 echo $e->getMessage();
} finally {
 echo 'Done';
}

$handle = fopen('data.txt', 'r');

$content = file_get_contents('data.txt');

file_put_contents('log.txt', 'Hello', FILE_APPEND);

if (file_exists('config.php')) { ... }

unlink('old_file.txt');

header('Location: login.php');
exit();

session_start();
$_SESSION['user_id'] = 5;

session_start();
session_unset();
session_destroy();

setcookie('user', 'John', time() + 3600);

echo $_COOKIE['user'] ?? 'Guest';

$conn = new mysqli('localhost', 'user', 'pass', 'mydb');
if ($conn->connect_error) { die($conn->connect_error); }

try {
 $pdo = new PDO('mysql:host=localhost;dbname=mydb', 'user', 'pass');
} catch (PDOException $e) {
 echo $e->getMessage();
}

$stmt = $pdo->query('SELECT * FROM users');
$users = $stmt->fetchAll(PDO::FETCH_ASSOC);

preg_match('/hello/i', 'HELLO World'); // matches

echo date('Y-m-d H:i:s');

echo date('Y-m-d', strtotime('next Friday'));

echo date('l, F j, Y', time());

{
 "require": {
 "monolog/monolog": "^3.0"
 }
}

echo get_class($car); // 'Car'

$name = $_GET['name'] ?? 'Guest';

$data['count'] ??= 0;

echo 1 <=> 2; // -1

echo '5' + 3; // 8

$num = (int) '123abc'; // 123

$s = 'a'; $s++; echo $s; // 'b'

$result = match($status) {
 1, 2 => 'active',
 0 => 'inactive',
 default => 'unknown',
};

foreach ($arr as &$val) { $val *= 2; }
unset($val);

function sum(...$nums) { return array_sum($nums); }

function increment(&$num) { $num++; }

function coords() { return [1, 2]; }
[$x, $y] = coords();

function factorial($n) {
 return $n <= 1 ? 1 : $n * factorial($n - 1);
}

$square = function($n) { return $n * $n; };
echo $square(4);

$factor = 2;
$multiply = function($n) use ($factor) { return $n * $factor; };

$multiply = fn($n) => $n * 2;

function add(int $a, int $b): int {
 return $a + $b;
}

declare(strict_types=1);

function find(?int $id): ?array { ... }

function hello() { echo 'Hi'; }
$fn = 'hello';
$fn();

function createUser(string $name, int $age = 18) {}
createUser(age: 25, name: 'Tom');

function logMessage(string $msg): void {
 echo $msg;
}

print_r(array_merge([1,2],[3,4])); // [1,2,3,4]
print_r([1,2] + [0=>9,2=>3]); // [1,2,3]

usort($people, fn($a, $b) => $a['age'] <=> $b['age']);

$squares = array_map(fn($n) => $n * $n, [1,2,3]);

$even = array_filter([1,2,3,4], fn($n) => $n % 2 == 0);

$total = array_reduce([1,2,3], fn($carry, $item) => $carry + $item, 0);

$combined = array_combine(['a','b'], [1,2]); // ['a'=>1,'b'=>2]

$a = [1, 2];
$b = [0, ...$a, 3]; // [0,1,2,3]

$names = array_column($users, 'name');

[$a, $b] = [1, 2];

var_dump(str_starts_with('hello world', 'hello')); // true

var_dump(str_contains('Hello World', 'World'));

echo sprintf('%s is %d years old', 'Tom', 25);

echo str_pad('5', 3, '0', STR_PAD_LEFT); // '005'

$fn = strlen(...);

class C { use A, B { A::hello insteadof B; B::hello as helloB; } }

class Bag {
 private array $data = [];
 function __get($name){ return $this->data[$name] ?? null; }
 function __set($name, $value){ $this->data[$name] = $value; }
}

class Adder {
 function __invoke($a, $b) { return $a + $b; }
}
$add = new Adder();
echo $add(2,3); // 5

$copy = clone $original;

$obj = new class {
 public function hello() { return 'hi'; }
};

set_error_handler(function($errno, $errstr) {
 echo "Error: $errstr";
});

$_SESSION['csrf'] = bin2hex(random_bytes(32));
// in form:
<input type='hidden' name='csrf' value='<?= $_SESSION['csrf'] ?>'>

preg_match('/<.+?>/', '<a><b>', $m); // matches '<a>' not '<a><b>'

#[Route('/users', methods: ['GET'])]
function listUsers() {}

function numbers() {
 for ($i = 1; $i <= 3; $i++) {
 yield $i;
 }
}
foreach (numbers() as $n) { echo $n; }

spl_autoload_register(function ($class) {
 include 'classes/' . $class . '.php';
});