Php Cheat Sheet

1. Variables


$variable = 'value'; // string variable
$variable = 10; // integer variable
$variable = 20.5; // floating-point variable

2. Data Types


string, integer, float, boolean, array, object, NULL

3. Operators


+, -, \*, /, %, ==, !=, >, <, >=, <=, &&, ||, !

4. Control Structures


if (condition) { code }
if (condition) { code } else { code }
switch (expression) { case value: code; break; }
for (init; condition; increment) { code }
while (condition) { code }
do { code } while (condition);

5. Loops


for ($i = 0; $i < 10; $i++) { code }
while ($i < 10) { code; $i++; }
do { code; $i++; } while ($i < 10);

6. Arrays


$fruits = array('apple', 'banana', 'orange');
$fruits = ['apple', 'banana', 'orange']; // shorthand syntax

7. Functions


function add($a, $b) { return $a + $b; }
function greet($name) { echo "Hello, $name!"; }

8. Classes


class Person {
    private $name;
    public function __construct($name) { $this->name = $name; }
    public function display() { echo "Name: $this->name"; }
}

9. Objects


$person = new Person('John Doe');
$person->display(); // prints "Name: John Doe"

10. Inheritance


class Animal {
    public function sound() { echo "The animal makes a sound."; }
}
class Dog extends Animal {
    public function sound() { echo "The dog barks."; }
}

11. Polymorphism


class Animal {
    public function sound() { echo "The animal makes a sound."; }
}
class Dog extends Animal {
    public function sound() { echo "The dog barks."; }
}
$animal = new Dog();
$animal->sound(); // prints "The dog barks."

12. Encapsulation


class Person {
    private $name;
    public function __construct($name) { $this->name = $name; }
    public function getName() { return $this->name; }
}

13. Abstraction


abstract class Animal {
    abstract public function sound();
}
class Dog extends Animal {
    public function sound() { echo "The dog barks."; }
}

14. Interface


interface Printable {
    public function print();
}
class Document implements Printable {
    public function print() { echo "Printing document..."; }
}

15. Exception Handling


try { code } catch (Exception $e) { code }

16. File Input/Output


$file = fopen('example.txt', 'r');
fscanf($file, '%d', $x);

17. Networking


$socket = socket_create(AF_INET, SOCK_STREAM, SOL_TCP);

18. Multithreading


class MyThread extends Thread {
    public function run() { /* code */ }
}
$thread = new MyThread();
$thread->start();

19. Lambda Functions


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

20. Namespaces


namespace MyNamespace;
class MyClass { }

21. Superglobals


$_GET, $_POST, $_SESSION, $_COOKIE, $_FILES, $_SERVER

22. Type Hinting


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

23. Null Coalescing Operator


$value = $input ?? 'default';

24. Ternary Operator


$result = ($condition) ? 'true' : 'false';

25. Array Functions


array_push($array, $value);
array_pop($array);

26. String Functions


strlen($string);
strpos($string, 'search');

27. Date and Time


$date = new DateTime();
echo $date->format('Y-m-d H:i:s');

28. JSON Handling


$json = json_encode($data);
$data = json_decode($json);

29. Sessions


session_start();
$_SESSION['key'] = 'value';

30. Cookies


setcookie('name', 'value', time() + 3600);

31. File Upload


if ($_FILES['file']['error'] == UPLOAD_ERR_OK) { /* code */ }

32. cURL


$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, 'http://example.com');
curl_exec($ch);
curl_close($ch);

33. Composer


require 'vendor/autoload.php';

34. PDO


$pdo = new PDO('mysql:host=localhost;dbname=test', 'user', 'pass');

35. Prepared Statements


$stmt = $pdo->prepare('SELECT * FROM users WHERE id = :id');
$stmt->execute(['id' => $id]);

36. Error Handling


set_error_handler(function($errno, $errstr) { /* code */ });

37. Autoloading


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

38. Traits


trait MyTrait { public function myMethod() { /* code */ } }
class MyClass { use MyTrait; }

39. Generators


function myGenerator() { yield 1; yield 2; }
foreach (myGenerator() as $value) { /* code */ }

40. Reflection


$reflection = new ReflectionClass('MyClass');
$methods = $reflection->getMethods();

41. Cloning Objects


$clone = clone $original;

42. Magic Methods


public function __get($name) { /* code */ }
public function __set($name, $value) { /* code */ }

43. Static Methods


class MyClass {
    public static function myStaticMethod() { /* code */ }
}

44. Static Properties


class MyClass {
    public static $myStaticProperty;
}

45. Constants


define ('MY_CONSTANT', 'value');
class MyClass {
    const MY_CLASS_CONSTANT = 'value';
}

46. Variable Variables


$varName = 'hello';
$$varName = 'world'; // $hello is now 'world'

47. Array Destructuring


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

48. Spread Operator


$array1 = [1, 2];
$array2 = [...$array1, 3, 4];

49. Nullsafe Operator


$result = $object?->method();

50. Match Expression


$result = match($value) {
    1 => 'one',
    2 => 'two',
    default => 'other',
};

51. Array Filter


$filtered = array_filter($array, fn($value) => $value > 0);

52. Array Map


$squared = array_map(fn($value) => $value ** 2, $array);

53. Array Reduce


$sum = array_reduce($array, fn($carry, $item) => $carry + $item, 0);

54. Array Slice


$sliced = array_slice($array, 1, 2);

55. Array Merge


$merged = array_merge($array1, $array2);

56. Array Unique


$unique = array_unique($array);

57. Array Keys


$keys = array_keys($array);

58. Array Values


$values = array_values($array);

59. Array Count


$count = count($array);

60. Array Push


array_push($array, $value);

61. Array Pop


$value = array_pop($array);

62. Array Shift


$value = array_shift($array);

63. Array Unshift


array_unshift($array, $value);

64. Array Fill


$filled = array_fill(0, 5, 'value');

65. Array Chunk


$chunks = array_chunk($array, 2);

66. Array Column


$column = array_column($array, 'column_name');

67. Array Combine


$combined = array_combine($keys, $values);

68. Array Diff


$difference = array_diff($array1, $array2);

69. Array Intersect


$intersection = array_intersect($array1, $array2);

70. Array Search


$key = array_search('value', $array);

71. Array Splice


array_splice($array, 1, 2);

72. Array Reverse


$reversed = array_reverse($array);

73. Array Sort


sort($array);

74. Array Shuffle


shuffle($array);

75. Array Map with Keys


$mapped = array_map(fn($value, $key) => "$key: $value", $array, array_keys($array));

76. Array Filter with Keys


$filtered = array_filter($array, fn($value, $key) => $key % 2 === 0, ARRAY_FILTER_USE_BOTH);

77. Array Reduce with Keys


$sum = array_reduce($array, fn($carry, $item) => $carry + $item, 0);

78. Array Count Values


$counts = array_count_values($array);

79. Array Pad


$padded = array_pad($array, 5, 'value');

80. Array Flip


$flipped = array_flip($array);

81. Array Is Array


$isArray = is_array($array);

82. Array Keys Exists


$exists = array_key_exists('key', $array);

83. Array Values Exists


$exists = in_array('value', $array);

84. Array Diff Key


$difference = array_diff_key($array1, $array2);

85. Array Intersect Key


$intersection = array_intersect_key($array1, $array2);

86. Array Merge Recursive


$merged = array_merge_recursive($array1, $array2);

87. Array Replace


$replaced = array_replace($array1, $array2);

88. Array Unique Recursive


$unique = array_unique($array, SORT_REGULAR);

89. Array Column with Objects


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

90. Array Group By


$grouped = [];
foreach ($array as $item) {
    $grouped[$item['key']][] = $item;
}

91. Array Random


$randomValue = $array[array_rand($array)];

92. Array Sum


$sum = array_sum($array);

93. Array Product


$product = array_product($array);

94. Array Diff Ukey


$difference = array_udiff_uassoc($array1, $array2, fn($a, $b) => $a - $b, fn($a, $b) => $a - $b);

95. Array Intersect Ukey


$intersection = array_uintersect_uassoc($array1, $array2, fn($a, $b) => $a - $b, fn($a, $b) => $a - $b);

96. Array Map with Keys


$mapped = array_map(fn($value, $key) => "$key: $value", $array, array_keys($array));

97. Array Filter with Keys


$filtered = array_filter($array, fn($value, $key) => $key % 2 === 0, ARRAY_FILTER_USE_BOTH);

98. Array Reduce with Keys


$sum = array_reduce($array, fn($carry, $item) => $carry + $item, 0);

99. Array Count Values


$counts = array_count_values($array);

100. Array Pad


$padded = array_pad($array, 5, 'value');