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Tuesday, November 2. 2010

PHP Quiz part 4 Posted by Mark van der Velden in PHP, PHPQuiz, PlanetPHP at 09:18

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PHP Quiz part 4

It has been a while, but here is part 4 of the PHP Quiz series! A few questions to crack your brain about, or perhaps you know them all? Try them and find out! Also do read the idea behind these quizzes, here: The PHP Quiz series

As always, think of the answer before you execute the code or look it up. Codepad might help you run the examples. You can find round three here.

 

Visibility is key

Now you see me, now you don't

class testClass {
    private $fubar = "rabuf";

    function test($test) {
        var_dump($test->fubar);
    }
}

class dummy {
    function test($test) {
        var_dump($test->fubar);
    }
}

$object1 = new testClass;
$object2 = new testClass;
$dummy = new dummy;

$object1->test($object1); // Can $object1 see the private property of object1 ?
$object1->test($object2); // Can $object1 see the private property of object2 ?
$dummy->test($object1); // Can $dummy see the private property of object1 ?
 

 

Static, sticky, icky

class test {
  public $counter = -1;

  public function increment() {
    static $cnt = 0;
    $this->counter = ++$cnt;
    return $this;
  }
}

$object1 = new test;
$object1->increment()->increment();

$object2 = new test;

// What will the output be
echo $object2->increment()->counter;

 

Getting the class

class b {
        function getClassA() {
                echo get_class($this);
        }
        function getClassB() {
                echo get_class();
        }
        function getClassC() {
                echo __CLASS__;
        }
}

class a extends b {
}

$a = new a;

// What will be returned, 'a' or 'b' ?
$a->getClassA();
$a->getClassB();
$a->getClassC();

 

The strptime function

$result = strptime('2010-11-28', '%Y-%m-%d');

// What is the output?
echo $result['tm_mday'] .'-'. $result['tm_mon'] .'-'. $result['tm_year'];
 

 

The oldtimer

for ($i = 0, $loop = 10, $a = 10; $i < $loop; ++$i, $a = 0) {
    ++$a;
}

// What is the output ?
echo $a;

Friday, September 25. 2009

The PHP Quiz series Posted by Mark van der Velden in PHPQuiz at 07:23

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The PHP Quiz series

I like solving puzzles, probably one of the reason why I like programming as much as I do. I also like finding challenges and experimenting, as such I came to the idea to start the PHP Quiz series. They contain typical combination of PHP quirks and lesser known features of PHP.

The reason behind the quizzes is not to advocate bad or good coding practices, but it's intended to let you find out the why in all of it. I believe that by understanding what happens it can make you a better programmer and you might spot bugs easier then without knowing what happens.

The series are not ordered in level of difficulty but merely in the order that I found out about them, thought about them or where simply sent in. But in general I think it's safe to say that your knowledge of PHP should be quite a leap forward from novice before you can answer most questions. This however doesn't mean that, once you can do the quizzes flawlessly, that you are a superior programmer. There is a big different between knowing how to design an application and knowing why $array = array(1,1) + array(2,2) only results in an array with two elements.

An overview of all the PHP Quizzes: http://blog.dynom.nl/categories/PHPQuiz_12


A special thanks to the people who sent in code samples, happy quizzing!

-D

Monday, September 21. 2009

PHP Quiz part 3 Posted by Mark van der Velden in PHP, PHPQuiz, PlanetPHP at 17:35

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PHP Quiz part 3

Welcome to another part of the PHP Quiz series, again some interesting questions to crack your brain about. If you have some nice additions or questions, be sure to leave a comment. Enjoy part three!

As always, think of the answer before you execute the code or look it up. You can find round two here.

Unset cast

What is the type of $a and what is the type of $b

$a = "A";
$b = (unset) $a;
var_dump($a, $b);
 

Form fun

What will the output be?

<form method="post" action="" enctype="text/plain">
    <input name="search" type="text">
    <input type="submit">
</form>
<?php
        error_reporting( E_ALL );
        echo (string) filter_input(INPUT_POST, 'search');
?>
 

Fun with strings

Strings in PHP are versatile, but how versatile are they... What will the output be?

$juggling = "Itffkhmf";
$rox = "Spy";
$b = $c = "";
for ($i=0; $i<strlen($juggling); $i++) {
    $b .= $juggling[ $i ];
    $b++;
}
for ($i=0; $i<strlen($rox); $i++) {
    $c .= $rox[ $i ];
    $c--;
}

var_dump( $b, $c );

Continue reading "PHP Quiz part 3"

Thursday, May 14. 2009

PHP Quiz part 2 Posted by Mark van der Velden in PHP, PHPQuiz, PlanetPHP at 10:41

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PHP Quiz part 2

A short quiz this time, but that doesn't make it less fun. Do you know the answer to all of them? Get a cup of coffee and kill 10 minutes with round two...

As always, think of the answer before you execute the code or look it up. You can find round one here.

Array pointer

What will the output be ?

$array = range(0,5);
next($array);
foreach($array as $v) {
  echo $v;
}
 

ArrayAccess and isset fun

isset or not isset, thats the question.

$a          = new ArrayObject;
$a['fubar'] = NULL;
$null       = NULL;

if (isset($null)) {
        echo 1;
} else {
        echo 2;
}

if (isset($a['fubar'])) {
        echo 1;
} else {
        echo 2;
}

if (array_key_exists('fubar', $a)) {
        echo 1;
} else {
        echo 2;
}

Typo?

The output might be confusing..

array(4>'a')

References

How many notices will be thrown?

error_reporting(E_ALL);
function a( & $array) {}
function b($array) {}
a($array);
b($array); 

Continue reading "PHP Quiz part 2"

Thursday, April 24. 2008

PHP Quiz part 1 Posted by Mark van der Velden in PHP, PHPQuiz, PlanetPHP at 21:50

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PHP Quiz part 1

Simple things of PHP can be just as fun as the advanced things in PHP!
To prove that I wanted to make a small quiz, and here it is.

Below you'll see 10 pieces of PHP5 code, the goal is to figure out the code and know the output before you actually run it.
Have fun!

Comment and closing tag

<?php // Without cheating.. What will you see when you run this single line of ?\?> php code

Echo print and get what

<?php
  // What do you expect from this ?
  echo print( 1 ); ?>

What wil eval to true

 <?php
  // How many times will we get 'true' ?

  $boolean  = false;
  echo ($boolean) ? 'true' : 'false';

  $boolean  = '0';
  echo ($boolean) ? 'true' : 'false';

  $boolean  = '00';
  echo ($boolean) ? 'true' : 'false';

Continue reading "PHP Quiz part 1"
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