PHP Cheat Sheet

<?php
echo "Hello, World!";

// Single line comment
# Also single line
/* Multi-line
   comment */

$name = "John";  // No type declaration
$age = 25;       // Dynamically typed

(int) "42"      // string to int
(string) 42     // int to string
(float) "3.14"  // to float

gettype($var)   // "string", "integer"
is_string($var) // true/false
is_array($var)  // true/false

$name = "John";

$age = 25;

$price = 19.99;

$isActive = true;

$fruits = ["apple", "banana", "cherry"];

$person = ["name" => "John", "age" => 30];

$value = null;

const PI = 3.14159;
define("MAX", 100);

+ - * /    // Add, Sub, Mul, Div
%          // Modulus
**         // Exponent
++ --      // Increment/Decrement

==   !=    // Equal (loose)
===  !==   // Equal (strict)
>    <     // Greater, Less
>=   <=    // Greater/Less or equal
<=>        // Spaceship (returns -1, 0, 1)

&&  and    // AND
||  or     // OR
!   // NOT
xor        // XOR

.    // Concatenation
.=   // Concatenate and assign
"Hello, $name"  // Interpolation

??   // Null coalescing
??=  // Null coalescing assignment
?->  // Nullsafe operator

=   +=  -=  *=  /=  %=
.=  // String concatenate assign
??= // Null coalescing assign

&   // AND
|   // OR
^   // XOR
~   // NOT
<<  // Left shift
>>  // Right shift

for ($i = 0; $i < 5; $i++) {
    echo $i;
}

foreach ($fruits as $fruit) {
    echo $fruit;
}

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

while ($count < 10) {
    $count++;
}

do {
    $count++;
} while ($count < 10);

for ($i = 0; $i < 10; $i++) {
    if ($i === 5) break;
}

for ($i = 0; $i < 10; $i++) {
    if ($i === 5) continue;
    echo $i;
}

foreach ($outer as $o) {
    foreach ($inner as $i) {
        if ($i === 5) break 2; // Breaks both
    }
}

array_map(fn($n) => $n * 2, $nums);
array_filter($nums, fn($n) => $n > 0);

if ($x > 0) {
    echo "positive";
} elseif ($x < 0) {
    echo "negative";
} else {
    echo "zero";
}

$result = $condition ? "yes" : "no";

$name = $user ?? "Guest";
$name = $user['name'] ?? "Unknown";

$result = match($day) {
    "Mon" => "Monday",
    "Tue", "Wed" => "Midweek",
    default => "Other"
};

switch ($day) {
    case "Mon":
        echo "Monday";
        break;
    default:
        echo "Other";
}

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

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

$square = fn($x) => $x * $x;

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

greet(name: "John", age: 30);

$doubled = array_map(fn($n) => $n * 2, $nums);

$evens = array_filter($nums, fn($n) => $n % 2 === 0);

$sum = array_reduce($nums, fn($a, $b) => $a + $b, 0);

$all = array_merge($arr1, $arr2);

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

$key = array_search("apple", $fruits);

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

    public function bark(): string {
        return "{$this->name} says woof!";
    }
}

class Puppy extends Dog {
    public function play(): string {
        return "{$this->name} is playing!";
    }
}

interface Animal {
    public function speak(): string;
}

trait Loggable {
    public function log(string $msg): void {
        echo $msg;
    }
}

try {
    $result = riskyOperation();
} catch (Exception $e) {
    echo $e->getMessage();
}

try {
    // code
} catch (Exception $e) {
    // handle
} finally {
    cleanup();
}

throw new InvalidArgumentException("Invalid input");

class MyException extends Exception {}

$greeting = "Hello, $name!";

$full = $first . " " . $last;

strlen($str);

substr($str, 0, 5);

str_replace("old", "new", $str);

explode(",", "a,b,c");

implode(",", ["a", "b", "c"]);