# [PHP](http://php.net)

PHP is a server-side scripting language designed for web development but also used as a general-purpose programming language. As of January 2013, PHP was installed on more than 240 million websites (39% of those sampled) and 2.1 million web servers. Originally created by Rasmus Lerdorf in 1994, the reference implementation of PHP (powered by the Zend Engine) is now produced by The PHP Group. While PHP originally stood for Personal Home Page, it now stands for PHP: Hypertext Preprocessor, which is a recursive backronym.

[Link][1] for myself, or anyone who wants to contribute to this answer.

**Length 11**

    ['a'=>[12]]

This statement is equal to `array('a'=>array(12))`, this short array syntax available since PHP 5.4.

**Length 10**

    $a=array()

This is an example on how to create an array, don't forget to add `;` at the end of the statement. The array will have empty length, you can check it using `sizeof` function. To append at the end of that array, you might use `[]=` operator, for example: `$a[] = 12`, this would append a number `12` to that array, that similar as typing `array(12)` at initialization.

**Length 9**

    phpinfo()

This [function][2] will print all information about current configuration and variables on your system.

**Length 8**

    __FILE__

Magic constant `__FILE__` is a constant that have different value depends on the file its being declared, there are also `__LINE__` that shows the line number where its being declared, and `__FUNCTION__` for function, `__DIR__` for directories (since PHP 5.3). You could see the full list [here][3]. They could be used as better way to implement includes, for example: `include dirname(__FILE__).'/file.php';` or `include __DIR__.'/file.php';`, credits: [@ismael-miguel][4] 

**Length 7**

    4**3**2

Exponentiation operator `**` is supported since PHP 5.6, the result of that execution is `262144` (from `64**2`)


**Length 6**

    $_POST

This is a global variable that holds value from http protocol with method `POST`, for example, if you have this form: `<form method='post'><input type='submit' name='a' value='b' /></form>', when that button clicked, the current php page could access the submitted value using `$_POST['a']` that would equal to `'b'` string.

**Length 5**

    <?=5?>

This is an example to write number 5 to output, this statement equal to `<?php echo 5; ?>`, don't forget to enable `short_open_tag` in your `php.ini` to enable this feature. 

**Length 4**

    NULL

`NULL` is a constant that holds the value of any variable that hasn't been set yet, or have been `unset`, or any variable/constant that has been assigned as `NULL`. 


**Length 3**

    1.2

This is example on how to create a [float][5] type value. Do not compare float values with equality `==` operator since they are [imprecise][6]. To check whether a variable is a float type, use `is_float` function.

**Length 2**

    ''

This is how you create an empty string in PHP, there are other way such as double quote `""`. For performance reason, always use single quote unless there are [interpolation][7].

**Length 1**

    a

Anything that written outside `<?` or `<?php` and `?>` are treated as output, so, if a `.php` file containing only a character `a`, that character itself would be the output.


**Factoid**

Some of the biggest [online sites][8], such as [Facebook][9], [Wikipedia][10], and [Yahoo!][11] are powered by PHP.


  [1]: https://codegolf.stackexchange.com/posts/44806/edit
  [2]: http://php.net/manual/en/function.phpinfo.php
  [3]: http://php.net/manual/en/language.constants.predefined.php
  [4]: https://codegolf.stackexchange.com/users/14732/ismael-miguel
  [5]: http://php.net/manual/en/language.types.float.php
  [6]: http://floating-point-gui.de/errors/comparison/
  [7]: http://php.net/manual/en/language.types.string.php
  [8]: https://en.wikipedia.org/wiki/Programming_languages_used_in_most_popular_websites
  [9]: http://facebook.com
  [10]: http://wikipedia.org
  [11]: http://yahoo.com