<?php echo "text"; ?>
<?= "shorthand echo" ?>
print "hello";
printf("%.2f", 3.14);
var_dump($x);    // type + value
print_r($arr);   // readable array
$x = sprintf("%.2f", 1.5); // return string

strlen($s)              // length
strtolower / strtoupper
str_contains($s, $q)    // PHP 8
str_starts_with / str_ends_with
str_replace($f, $r, $s)
substr($s, $start, $len)
strpos($s, $needle)
trim / ltrim / rtrim
explode(",", $s) → array
implode(",", $arr) → string
sprintf("%.2f", 3.14)
number_format(1234.5, 2)

count($a)
array_push($a, $v) / $a[] = $v
array_pop / array_shift / array_unshift
array_merge($a, $b)
array_slice($a, $s, $l)
array_map($fn, $a)
array_filter($a, $fn)
array_reduce($a, $fn, $init)
array_search($val, $a)
in_array($val, $a, true)
array_unique / array_flip
array_column($arr, "name")
sort / rsort / usort / uksort

abs / round / ceil / floor
max / min / rand($min, $max)
pow(2, 8)   // 256
sqrt(144)   // 12
fmod(10, 3) // 1.0
intdiv(7, 2) // 3
number_format(1234.5, 2)
M_PI   M_E   PHP_INT_MAX

date("Y-m-d")         // "2024-03-15"
date("H:i:s")         // "14:30:00"
time()                // Unix timestamp
strtotime("next monday")
new DateTime("now")
$dt->format("Y-m-d H:i")
$dt->modify("+1 week")
date_diff($d1, $d2)->days

header("Location: /page.php");
header("Content-Type: application/json");
http_response_code(404);
setcookie("name","val",time()+3600);
$_SERVER["REQUEST_METHOD"]
$_SERVER["REQUEST_URI"]
$_SERVER["HTTP_HOST"]
$_SERVER["REMOTE_ADDR"]

htmlspecialchars($s, ENT_QUOTES, "UTF-8")
strip_tags($html)
filter_input(INPUT_POST, "k", FILTER_VALIDATE_EMAIL)
password_hash($p, PASSWORD_BCRYPT)
password_verify($p, $hash)
bin2hex(random_bytes(32)) // CSRF token
hash("sha256", $data)

$pdo = new PDO($dsn, $u, $p, $opts);
$stmt = $pdo->prepare("SELECT...");
$stmt->execute([$val]);
$row  = $stmt->fetch();
$rows = $stmt->fetchAll();
$pdo->lastInsertId();
$stmt->rowCount();
$pdo->beginTransaction();
$pdo->commit();
$pdo->rollBack();

// Constructor promotion (PHP 8)
class User {
  public function __construct(
    private readonly int $id,
    private string $name
  ) {}
}

// Enum (PHP 8.1)
enum Status: string {
  case Active   = "active";
  case Inactive = "inactive";
}

// Named arguments
array_slice(arr: $a, offset: 2);

// Nullsafe operator
$city = $user?->address?->city;

// Match expression
$r = match($n) {
  1, 2 => "low",
  3    => "mid",
  default => "high",
};

// Union types
function f(int|string $v): void {}

file_get_contents($path)
file_put_contents($p, $data)
file_put_contents($p, $d, FILE_APPEND)
file($p, FILE_IGNORE_NEW_LINES)
file_exists($p)
filesize($p) / filemtime($p)
pathinfo($p)  // dir/base/ext
mkdir($p, 0755, true)
scandir($dir)
glob("*.php")
unlink($file)