phpitfalls - cologne

Transcript

1. PHPitfalls
 Symfony User Group Cologne
2. HERE BE DRAGONS Copyright ▸ Symfony User Group Berlin ▸ Alexander Turek ▸ Christopher Hertel ▸ Denis Brumann
4. RULES
5. HERE COULD BE YOUR ADVERTISING Rules ▸ 3 Rounds ▸ Qualification Round ▸ Main Round ▸ Final Round ▸ Runtime is PHP 7.0/7.1/7.2 ▸ Don’t cheat! (no mobile devices) ▸ Be fair
6. MOTIVATION?!
8. LET’S START
9. ROUND 1 QUALIFICATION
10. GOOD LUCK Round 1 - Qualification ▸ Take a quiz ▸ Take a pen ▸ Answer the 5 questions (single choice) ▸ Hand the quiz to us ▸ Have a beer & wait for the next round
12. QUESTION 1 What is the output of this code snippet? $a = 5; echo $a++ + $a++; 11 A 10 C 12 D 13 B
13. QUESTION 1 What is the output of this code snippet? $a = 5; echo $a++ + $a++; 11 A 10 C 12 D 13 B
14. QUESTION 2 What is the output of this code snippet? var_dump(true ? 'Foo' : false ? 'Bar' : 'Baz'); string(3) Foo A string(3) Bar C string(3) Baz D bool(false) B
15. QUESTION 2 What is the output of this code snippet? var_dump(true ? 'Foo' : false ? 'Bar' : 'Baz'); string(3) Foo A string(3) Bar C string(3) Baz D bool(false) B
16. QUESTION 3 What is the output of this code snippet? $x = 0; echo 'Hello ' . $x+42 . ' World'; Fatal Error A Hello 43 C Hello 42 World D 42 World B
17. QUESTION 3 What is the output of this code snippet? $x = 0; echo 'Hello ' . $x+42 . ' World'; Fatal Error A Hello 43 C Hello 42 World D 42 World B
18. QUESTION 4 Which array key will be overridden? '0' A 0135 B 135 C $array = [ 'test' => 'foo', '0' => 'bar', 0135 => 'baz', 135 => 'x', '0135' => 'y', ’135’ => 'omg', '0.0' => 'yeah' ]; Nothing D
19. QUESTION 4 Which array key will be overridden? '0' A 0135 B 135 C Nothing D $array = [ 'test' => 'foo', '0' => 'bar', 0135 => 'baz', 135 => 'x', '0135' => 'y', ’135’ => 'omg', '0.0' => 'yeah' ];
20. QUESTION 5 What is the output of this code snippet? $versions = ['7.1', '7.2', '7.3']; var_dump(in_array('7.10', $versions)); bool(false) A bool(true) B
21. QUESTION 5 What is the output of this code snippet? $versions = ['7.1', '7.2', '7.3']; var_dump(in_array('7.10', $versions)); bool(false) A bool(true) B
22. ROUND 2 MAIN ROUND
23. QUESTION 6 What is the output of this code snippet? echo(print('symfony')); symfonysymfony A symfony C symfony7 D symfony1 B
24. QUESTION 6 What is the output of this code snippet? echo(print('symfony')); symfonysymfony A symfony C symfony7 D symfony1 B
25. QUESTION 7 What is the output of this code snippet? $a = "1d9"; $a++; $a++; echo $a; 2 A 0 C fatal error D 1e1 B
26. QUESTION 7 What is the output of this code snippet? $a = "1d9"; $a++; $a++; echo $a; 2 A 0 C fatal error D 1e1 B
27. QUESTION 8 What is the output of this code snippet? list($a, $a) = array(1, 2, 3, 4); var_dump($a); Fatal error A int(1) C int(2) D int(4) B
28. QUESTION 8 What is the output of this code snippet? list($a, $a) = array(1, 2, 3, 4); var_dump($a); Fatal error A int(1) C int(2) D int(4) B BTW: BC BREAK OF PHP 7
29. QUESTION 9 What is the output of this code snippet? $array = [ 9223372036854775807 => 6, 5076964154930102272 => 2, 999999999999999999999999999999 => 4, ]; var_dump(array_sum($array)); int(12) A int(8) C int(10) D int(6) B
30. QUESTION 9 What is the output of this code snippet? $array = [ 5076964154930102272 => 2, 999999999999999999999999999999 => 4, ]; var_dump(array_sum($array)); int(6) A int(2) C int(-2) D int(4) B $array = [ 9223372036854775807 => 6, 5076964154930102272 => 2, 999999999999999999999999999999 => 4, ]; var_dump(array_sum($array)); int(12) A int(8) C int(10) D int(6) B
31. QUESTION 10 What is the output of this code snippet? $array = [1, 2, 3]; foreach ($array as &$v) {} foreach ($array as $v) {} var_dump(array_sum($array)); 1 A 5 C 6 D 9 B
32. QUESTION 10 What is the output of this code snippet? $array = [1, 2, 3]; foreach ($array as &$v) {} foreach ($array as $v) {} var_dump(array_sum($array)); 1 A 5 C 6 D 9 B
33. QUESTION 11 What is the output of this code snippet? function compare($a, $b, $c) { echo (int)($a < $b); echo (int)($b < $c); echo (int)($c < $a); } compare('066', '07x', '28'); 010 A 111 C 001 D 110 B
34. QUESTION 11 What is the output of this code snippet? function compare($a, $b, $c) { echo (int)($a < $b); echo (int)($b < $c); echo (int)($c < $a); } compare('066', '07x', '28'); 010 A 111 C 001 D 110 B
35. QUESTION 12 What is the output of this code snippet? namespace Foo { class Bar { } } namespace { echo(Bar::class); } Bar A Fatal Error C empty output D Foo\Bar B
36. QUESTION 12 What is the output of this code snippet? namespace Foo { class Bar { } } namespace { echo(Bar::class); } Bar A Fatal Error C empty output D Foo\Bar B
37. QUESTION 13 What is the output of this code snippet? function foo() { try { return 1337; } finally { return 42; } } var_dump(foo()); int(1337) A string(6) 133742 C int(42) D Fatal Error B
38. QUESTION 13 What is the output of this code snippet? function foo() { try { return 1337; } finally { return 42; } } var_dump(foo()); int(1337) A string(6) 133742 C int(42) D Fatal Error B
39. QUESTION 14 What is the output of this code snippet? $date = new \DateTimeImmutable('2018-01-24'); $date->__construct('2017-12-24'); echo $date->format('d.m.Y'); bool(true) A bool(false) B Fatal Error A 24.12.2017 C 24.01.2018 D 24.01.18 B
40. QUESTION 14 What is the output of this code snippet? $date = new \DateTimeImmutable('2018-01-24'); $date->__construct('2017-12-24'); echo $date->format('d.m.Y'); bool(true) A bool(false) B Fatal Error A 24.12.2017 C 24.01.2018 D 24.01.18 B
41. QUESTION 15 What is the output of this code snippet? $objects = [new \stdClass()]; var_dump(in_array((object)[], $objects)); bool(true) A bool(false) B fatal error C D segmentation fault
42. QUESTION 15 What is the output of this code snippet? $objects = [new \stdClass()]; var_dump(in_array((object)[], $objects)); bool(true) A bool(false) B fatal error C D segmentation fault
43. ROUND 3 FINAL
44. QUESTION 16 What is the output of this code snippet? echo(printf('hello world'));
45. QUESTION 16 What is the output of this code snippet? echo(printf('hello world')); hello world11
46. QUESTION 17 What is the output of this code snippet? echo 1...1;
47. QUESTION 17 What is the output of this code snippet? echo 1...1; 10.1
48. QUESTION 18 Which number is displayed? use const true as false; if (false) { echo 1; } if (true) { echo 2; } if (true === false) { echo 3; } if (\false) { echo 4; } if (\true) { echo 5; } if (2 > 1) { echo 6; }
49. QUESTION 18 Which number is displayed? use const true as false; if (false) { echo 1; } if (true) { echo 2; } if (true === false) { echo 3; } if (\false) { echo 4; } if (\true) { echo 5; } if (2 > 1) { echo 6; } 12356
50. QUESTION 19 Which string is displayed? class Foo { public $bar = 'foo'; static function create() { $foo = new self(); $foo->bar .= 'foo'; $foo->foo(); return $foo; } private function foo() { $this->bar .= 'bar'; } } $foo = Foo::create(); echo $foo->bar;
51. QUESTION 19 Which string is displayed? foobarfoobar class Foo { public $bar = 'foo'; static function create() { $foo = new self(); $foo->bar .= 'foo'; $foo->foo(); return $foo; } private function foo() { $this->bar .= 'bar'; } } $foo = Foo::create(); echo $foo->bar;
52. QUESTION 20 What is the output of file2.php? // include.php $a = 5; $b = 1; var_dump($a + $b); // main.php $b = new class { function __destruct(){ $GLOBALS['b'] = 5; } }; require 'include.php';
53. QUESTION 20 What is the output of file2.php? // include.php $a = 5; $b = 1; var_dump($a + $b); // main.php $b = new class { function __destruct(){ $GLOBALS['b'] = 5; } }; require 'include.php'; int(10) Credits: Nikita Popov - Static Optimization of PHP Bytecode
54. GAME OVER
55. THANKS