PHP Cheat Sheet

<?php
echo 'Hello, World!';

$greeting = 'Hello, World!';
echo $greeting; // Hello, World!

const CONSTANT = 'value';
define('RUNTIME_CONSTANT', CONSTANT);

echo CONSTANT; // value
echo RUNTIME_CONSTANT; // value

$name = 'World';
echo 'Hello, $name!'; // Hello, $name!
echo "Hello, $name!'; // Hello, World!
echo "Hello, {$name}!"; // Hello, World!

echo <<<END
This is a multi-line string
in HEREDOC syntax (with interpolation).
END;

echo <<<'END'
This is a multi-line string
in NOWDOC syntax (without interpolation).
END;

$array = [1, 2, 3];
$array[] = 4;
$array[4] = 5;

function foo(int $a, int $b = 5): int
{
    return $a + $b;
}
foo(1, 2); // 3
foo(1); // 6

function foo(string $a, string $b): string
{
    return $a . $b;
}
foo(b: 'World!', a: 'Hello, '); // Hello, World!

$y = 3;
$foo = function(int $x) use($y): int {
    return $x + $y;
};
$foo(1); // 4

$y = 3;
$foo = fn(int $x): int => $x + $y;
$foo(1); // 4

function generate(): interable
{
    yield 1;
    yield 2;
}

foreach(generate() as $value) {
    echo $value;
}

// This is a one line C++ style comment
# This is a one line shell-style comment
/* This is a
   multi-line comment */

/**
 * This is a PHPDoc docblock
 * @param string[] $bar
 * @return void
 */
function foo(array $bar): void
{}

if ($a > $b) {
    echo "a is greater than b";
} elseif ($a == $b) {
    echo "a is equal to b";
} else {
    echo "a is less than b";
}

while ($i < 10) {
    echo $i++;
}

do {
    echo $i++;
} while ($i < 10);

for ($i = 0; $i < 10; $i++) {
    echo $i;
}

foreach ($array as $value) {
    echo $value;
}

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

switch ($i) {
    case 0:
    case 1:
        echo "i equals 0 or 1";
        break;
    default:
        echo "i is not equal to 0 or 1";
}

$foo = match($i) {
    0 => "i is 0",
    1, 2 => "i is 1 or 2",
    default => "i is not 0, 1 or 2",
};

enum Suit {
    case Hearts;
    case Diamonds;
    case Clubs;
    case Spades;
}

$suit = Suit::Hearts;
$suit->name; // Hearts

enum Suit: string {
    case Hearts = '♥';
    case Diamonds = '♦';
    case Clubs = '♣';
    case Spades = '♠';
}

$hearts = Suit::from('♥');
$hearts->value; // '♥'

interface FooInterface
{
    public function baz(): string;
}

class Foo extends Bar implements FooInterface
{
    private string $bar;
    public const string BAZ = 'Hello, ';

    public function __construct(string $bar)
    {
        $this->bar = $bar;
    }

    public function baz(): string
    {
        return self::BAZ . $this->bar;
    }
}
$foo = new Foo("World!");
echo $foo->baz(); // Hello, World!'
echo Foo::BAZ; // Hello,

class Foo
{
    public function __construct(private string $bar)
    {}
}

class Foo
{
    public string $name {
        set (string $value) {
            $this->name = strtolower($value);
        }
        get => ucfirst($this->name);
    }
}

class Foo
{
    public private(set) string $bar = 'baz';
}

$foo = new Foo();
echo $foo->bar; // baz
$foo->bar = 'Foobar'; // Error

namespace Foo\Bar;
use Foo\Baz as BazAlias;
use Foo\Baz\{Qux, Quux};
use function strlen;
use const PHP_EOL;

try {
    throw new Exception('Something went wrong');
} catch (Exception $e) {
    // Code that runs when an exception is thrown
} finally {
    // Code that will always run
}

trait FooTrait
{
    public function baz(): string { ... }
}
class Foo
{
    use FooTrait;
}

#[Attribute(flags: Attribute::TARGET_CLASS)]
class MyClassAttribute
{}

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