PHP Cheat Sheet

<?php
// Standard PHP tag
 
echo "Hello World";
 
// Short echo tag (always available)
<?= "Hello World" ?>
 
// Inline PHP
<?php echo "Hello"; ?>

<?php
// Single line comment
 
# Single line comment (style Unix)
 
/*
 * Multi-line comment
 * Bisa banyak baris
 */
 
/**
 * DocBlock comment
 * Buat dokumentasi function/class
 */

<?php
// Echo - bisa multiple parameters
echo "Hello", " ", "World";
echo "Hello World";
 
// Print - cuma satu parameter, return value
print "Hello World";
 
// Print_r - buat debug array/object
print_r($array);
 
// Var_dump - detailed info dengan type
var_dump($variable);
 
// Var_export - output valid PHP code
var_export($array);

<?php
// Variable diawali $
$name = "Budi";
$age = 25;
$price = 99.99;
 
// Variable variables
$var = "hello";
$$var = "world";
echo $hello; // Output: world
 
// Constants
define('PI', 3.14159);
const API_KEY = 'abc123';
 
echo PI; // 3.14159
echo API_KEY; // abc123

<?php
// String
$name = "Budi";
$greeting = 'Hello';
 
// Integer
$age = 25;
$hex = 0x1A; // Hexadecimal
$binary = 0b1010; // Binary
 
// Float
$price = 99.99;
$scientific = 1.2e3; // 1200
 
// Boolean
$isActive = true;
$isDone = false;
 
// Array
$numbers = [1, 2, 3, 4, 5];
$person = ['name' => 'Budi', 'age' => 25];
 
// Null
$nothing = null;
 
// Object
$obj = new stdClass();
$obj->name = "Budi";
 
// Resource
$file = fopen('file.txt', 'r');

<?php
// Check types
is_string($var);
is_int($var);
is_float($var);
is_bool($var);
is_array($var);
is_object($var);
is_null($var);
is_numeric($var);
 
// Get type
gettype($var);
 
// Type casting
$str = (string) 123;
$int = (int) "123";
$float = (float) "99.99";
$bool = (bool) 1;
$array = (array) $obj;

<?php
// Concatenation
$fullName = $firstName . " " . $lastName;
$text = "Hello" . " " . "World";
 
// String interpolation (double quotes)
$name = "Budi";
echo "Hello, $name";
echo "Hello, {$name}";
 
// Heredoc
$text = <<<EOT
Multi-line string
Variables: $name
EOT;
 
// Nowdoc (tanpa parsing variable)
$text = <<<'EOT'
Variables won't be parsed: $name
EOT;

<?php
$str = "Hello World";
 
// Length
strlen($str); // 11
 
// Position
strpos($str, "World"); // 6
strrpos($str, "o"); // 7 (last occurrence)
 
// Case
strtoupper($str); // HELLO WORLD
strtolower($str); // hello world
ucfirst($str); // Hello world
ucwords($str); // Hello World
 
// Substring
substr($str, 0, 5); // Hello
substr($str, 6); // World
 
// Replace
str_replace("World", "PHP", $str); // Hello PHP
str_ireplace("world", "PHP", $str); // Case-insensitive
 
// Trim
trim(" hello "); // "hello"
ltrim(" hello"); // "hello"
rtrim("hello "); // "hello"
 
// Split & Join
explode(" ", $str); // ["Hello", "World"]
implode(", ", $array); // "a, b, c"
 
// Contains (PHP 8+)
str_contains($str, "World"); // true
str_starts_with($str, "Hello"); // true
str_ends_with($str, "World"); // true

<?php
// Indexed array
$fruits = ["Apple", "Banana", "Orange"];
$numbers = array(1, 2, 3, 4, 5);
 
// Associative array
$person = [
  "name" => "Budi",
  "age" => 25,
  "city" => "Jakarta"
];
 
// Multi-dimensional array
$users = [
  ["name" => "Budi", "age" => 25],
  ["name" => "Ani", "age" => 22]
];

<?php
$arr = [1, 2, 3, 4, 5];
 
// Add elements
array_push($arr, 6); // Add to end
$arr[] = 6; // Shorthand
array_unshift($arr, 0); // Add to beginning
 
// Remove elements
array_pop($arr); // Remove last
array_shift($arr); // Remove first
 
// Count
count($arr); // 5
sizeof($arr); // Alias of count
 
// Check existence
in_array(3, $arr); // true
array_key_exists("name", $person); // true
isset($person["name"]); // true
 
// Merge
array_merge($arr1, $arr2);
[...$arr1, ...$arr2]; // Spread operator
 
// Slice & Splice
array_slice($arr, 1, 3); // Get portion
array_splice($arr, 1, 2, [10, 20]); // Remove & insert
 
// Search
array_search("Banana", $fruits); // Return key
array_keys($person); // ["name", "age", "city"]
array_values($person); // ["Budi", 25, "Jakarta"]
 
// Sort
sort($arr); // Ascending
rsort($arr); // Descending
asort($arr); // Sort preserving keys
ksort($arr); // Sort by keys
 
// Map, Filter, Reduce
array_map(fn($n) => $n * 2, $arr);
array_filter($arr, fn($n) => $n > 2);
array_reduce($arr, fn($carry, $item) => $carry + $item, 0);
 
// PHP 8.4: New array functions
array_find($arr, fn($n) => $n > 3); // Find first match
array_find_key($arr, fn($n) => $n > 3); // Find key
array_any($arr, fn($n) => $n > 3); // Check if any match
array_all($arr, fn($n) => $n > 0); // Check if all match

<?php
if ($age >= 18) {
  echo "Dewasa";
} elseif ($age >= 13) {
  echo "Remaja";
} else {
  echo "Anak-anak";
}
 
// Ternary
$status = $age >= 18 ? "Dewasa" : "Belum dewasa";
 
// Null coalescing
$name = $_GET['name'] ?? 'Guest';
 
// Null coalescing assignment (PHP 7.4+)
$name ??= 'Default';

<?php
switch ($day) {
  case 'Monday':
    echo "Senin";
    break;
  case 'Friday':
    echo "Jumat";
    break;
  default:
    echo "Hari lain";
}
 
// Match expression (PHP 8+)
$result = match($day) {
  'Monday' => 'Senin',
  'Friday' => 'Jumat',
  default => 'Hari lain'
};

<?php
// For loop
for ($i = 0; $i < 10; $i++) {
  echo $i;
}
 
// While loop
$i = 0;
while ($i < 10) {
  echo $i;
  $i++;
}
 
// Do-while loop
do {
  echo $i;
  $i++;
} while ($i < 10);
 
// Foreach loop
foreach ($fruits as $fruit) {
  echo $fruit;
}
 
foreach ($person as $key => $value) {
  echo "$key: $value";
}
 
// Break & Continue
for ($i = 0; $i < 10; $i++) {
  if ($i == 5) break;
  if ($i == 3) continue;
  echo $i;
}

<?php
// Basic function
function greet($name) {
  return "Hello, $name";
}
 
// Default parameters
function greet($name = "Guest") {
  return "Hello, $name";
}
 
// Type declarations
function add(int $a, int $b): int {
  return $a + $b;
}
 
// Multiple return types (PHP 8+)
function getValue(): int|string {
  return rand(0, 1) ? 42 : "forty-two";
}
 
// Nullable types
function getName(): ?string {
  return null;
}
 
// Void return
function logMessage(string $message): void {
  echo $message;
}

<?php
// Short syntax
$double = fn($n) => $n * 2;
 
// Auto-capture variables
$multiplier = 3;
$triple = fn($n) => $n * $multiplier;
 
// With array functions
array_map(fn($n) => $n * 2, $numbers);

<?php
$func = 'greet';
$func('Budi'); // Call greet('Budi')
 
// Anonymous function
$greet = function($name) {
  return "Hello, $name";
};
 
// Closure with use
$multiplier = 3;
$multiply = function($n) use ($multiplier) {
  return $n * $multiplier;
};

<?php
class Person {
  // Properties
  public string $name;
  private int $age;
  protected string $email;
 
  // Constructor
  public function __construct(string $name, int $age) {
    $this->name = $name;
    $this->age = $age;
  }
 
  // Methods
  public function greet(): string {
    return "Hello, I'm {$this->name}";
  }
 
  // Getter
  public function getAge(): int {
    return $this->age;
  }
 
  // Setter
  public function setAge(int $age): void {
    $this->age = $age;
  }
}
 
// Create object
$person = new Person("Budi", 25);
echo $person->greet();

<?php
class User {
  // Property dengan hooks
  public string $name {
    // Get hook
    get => strtoupper($this->name);
    // Set hook
    set => ucfirst($value);
  }
 
  public int $age {
    set {
      if ($value < 0) {
        throw new ValueError("Age must be positive");
      }
      $this->age = $value;
    }
  }
}
 
$user = new User();
$user->name = "budi"; // Stored as "Budi"
echo $user->name; // Output: BUDI

<?php
class Animal {
  protected string $name;
 
  public function __construct(string $name) {
    $this->name = $name;
  }
 
  public function makeSound(): string {
    return "Some sound";
  }
}
 
class Dog extends Animal {
  public function makeSound(): string {
    return "Woof!";
  }
 
  public function wagTail(): void {
    echo "{$this->name} is wagging tail";
  }
}
 
$dog = new Dog("Buddy");
echo $dog->makeSound(); // Woof!

<?php
// Interface
interface Drivable {
  public function drive(): void;
  public function stop(): void;
}
 
class Car implements Drivable {
  public function drive(): void {
    echo "Driving...";
  }
 
  public function stop(): void {
    echo "Stopping...";
  }
}
 
// Trait
trait Loggable {
  public function log(string $message): void {
    echo "[LOG] $message";
  }
}
 
class User {
  use Loggable;
}
 
$user = new User();
$user->log("User created");

<?php
abstract class Shape {
  abstract public function area(): float;
 
  public function describe(): string {
    return "This is a shape";
  }
}
 
class Circle extends Shape {
  private float $radius;
 
  public function __construct(float $radius) {
    $this->radius = $radius;
  }
 
  public function area(): float {
    return pi() * $this->radius ** 2;
  }
}

<?php
class Status {
  public const string ACTIVE = 'active';
  public const string INACTIVE = 'inactive';
  public const int MAX_RETRY = 3;
}

<?php
class User {
  // Public read, private write
  public private(set) string $username;
 
  public function __construct(string $username) {
    $this->username = $username;
  }
}
 
$user = new User("budi");
echo $user->username; // OK
// $user->username = "ani"; // Error!

<?php
// Tanpa null safe
$country = null;
if ($user !== null) {
  $country = $user->getAddress()?->getCountry();
}
 
// Dengan null safe
$country = $user?->getAddress()?->getCountry();

<?php
function createUser(
  string $name,
  int $age,
  string $email = '',
  bool $active = true
) {
  // ...
}
 
// Skip parameters
createUser(
  name: "Budi",
  age: 25,
  active: false
);

<?php
$result = match($status) {
  'pending' => 'Waiting',
  'approved', 'confirmed' => 'Accepted',
  'rejected' => 'Denied',
  default => 'Unknown'
};
 
// Dengan kondisi
$fee = match(true) {
  $age < 18 => 0,
  $age < 65 => 10,
  default => 5
};

<?php
#[Route('/api/users')]
class UserController {
  #[Get]
  #[Cached(seconds: 3600)]
  public function index() {
    // ...
  }
}

<?php
enum Status {
  case Pending;
  case Approved;
  case Rejected;
}
 
enum Status: string {
  case Pending = 'pending';
  case Approved = 'approved';
  case Rejected = 'rejected';
 
  public function label(): string {
    return match($this) {
      self::Pending => 'Menunggu',
      self::Approved => 'Disetujui',
      self::Rejected => 'Ditolak',
    };
  }
}
 
$status = Status::Pending;
echo $status->value; // 'pending'
echo $status->label(); // 'Menunggu'

<?php
class User {
  public function __construct(
    public readonly string $id,
    public readonly string $name,
  ) {}
}
 
$user = new User('123', 'Budi');
// $user->name = 'Ani'; // Error!

<?php
readonly class Config {
  public function __construct(
    public string $apiKey,
    public string $apiUrl,
  ) {}
}

<?php
try {
  // Code yang mungkin error
  $result = riskyOperation();
} catch (Exception $e) {
  // Handle error
  echo "Error: " . $e->getMessage();
} finally {
  // Always execute
  cleanup();
}
 
// Multiple catch
try {
  // ...
} catch (TypeError $e) {
  echo "Type error";
} catch (ValueError $e) {
  echo "Value error";
} catch (Exception $e) {
  echo "General error";
}

<?php
class UserNotFoundException extends Exception {}
 
function findUser($id) {
  if (!userExists($id)) {
    throw new UserNotFoundException("User not found");
  }
  return getUser($id);
}
 
try {
  $user = findUser(123);
} catch (UserNotFoundException $e) {
  echo $e->getMessage();
}

<?php
#[\Deprecated(
  message: "Use newMethod() instead",
  since: "1.5.0"
)]
function oldMethod() {
  // ...
}

<?php
// Read entire file
$content = file_get_contents('file.txt');
 
// Read as array
$lines = file('file.txt');
 
// Read with fopen
$file = fopen('file.txt', 'r');
while (!feof($file)) {
  $line = fgets($file);
  echo $line;
}
fclose($file);

<?php
// Write string to file
file_put_contents('file.txt', 'Hello World');
 
// Append to file
file_put_contents('file.txt', 'More content', FILE_APPEND);
 
// Write with fopen
$file = fopen('file.txt', 'w');
fwrite($file, 'Hello World');
fclose($file);

<?php
// Check existence
file_exists('file.txt');
is_file('file.txt');
is_dir('directory');
 
// File info
filesize('file.txt');
filemtime('file.txt'); // Last modified time
 
// Copy, rename, delete
copy('source.txt', 'dest.txt');
rename('old.txt', 'new.txt');
unlink('file.txt'); // Delete
 
// Directory operations
mkdir('directory');
rmdir('directory');
scandir('directory');

<?php
try {
  $pdo = new PDO(
    'mysql:host=localhost;dbname=mydb',
    'username',
    'password',
    [PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION]
  );
} catch (PDOException $e) {
  die("Connection failed: " . $e->getMessage());
}

<?php
// Select
$stmt = $pdo->query("SELECT * FROM users");
$users = $stmt->fetchAll(PDO::FETCH_ASSOC);
 
// Prepared statements (prevent SQL injection!)
$stmt = $pdo->prepare("SELECT * FROM users WHERE id = ?");
$stmt->execute([$userId]);
$user = $stmt->fetch();
 
// Named parameters
$stmt = $pdo->prepare("SELECT * FROM users WHERE email = :email");
$stmt->execute(['email' => $email]);
 
// Insert
$stmt = $pdo->prepare("INSERT INTO users (name, email) VALUES (?, ?)");
$stmt->execute([$name, $email]);
$lastId = $pdo->lastInsertId();
 
// Update
$stmt = $pdo->prepare("UPDATE users SET name = ? WHERE id = ?");
$stmt->execute([$name, $id]);
 
// Delete
$stmt = $pdo->prepare("DELETE FROM users WHERE id = ?");
$stmt->execute([$id]);

{
  "require": {
    "monolog/monolog": "^3.0"
  },
  "autoload": {
    "psr-4": {
      "App\\": "src/"
    }
  }
}

# Install dependencies
composer install
 
# Update dependencies
composer update
 
# Add package
composer require vendor/package
 
# Remove package
composer remove vendor/package
 
# Dump autoload
composer dump-autoload

<?php
require 'vendor/autoload.php';
 
use App\Models\User;
use Monolog\Logger;
 
$user = new User();
$logger = new Logger('app');

<?php
// Always use type declarations
function processUser(User $user): bool {
  // ...
}
 
// Strict types (recommended)
declare(strict_types=1);

<?php
// Enable error reporting di development
error_reporting(E_ALL);
ini_set('display_errors', 1);
 
// Disable di production
error_reporting(0);
ini_set('display_errors', 0);

<?php
// Prevent XSS
echo htmlspecialchars($userInput, ENT_QUOTES, 'UTF-8');
 
// Prevent SQL injection
$stmt = $pdo->prepare("SELECT * FROM users WHERE id = ?");
$stmt->execute([$id]);
 
// Password hashing
$hash = password_hash($password, PASSWORD_DEFAULT);
$verified = password_verify($password, $hash);
 
// CSRF protection
session_start();
$_SESSION['csrf_token'] = bin2hex(random_bytes(32));