PHP
			===

Variables:
----------

$variable_name = value;

global $g_var = value;

static $s_var = value;

function birthday(){...}


PHP super globals:
------------------
$GLOBALS
$_SERVER
$_GET
$_POST
$_COOKIE
$_FILES
$_ENV
$_REQUEST
$_SESSION

ex: in a file names "test.php"
echo $_SERVER["PHP_SELF"];
output: /test.php

Strings:
--------

$str = "world";
echo "Hello $str";
$str.= "y"; 		// Concatenation

* You can't include variables when using single quotes.

\n - new line
\r - return
\t - tab
\$ - dollar sign
\" - double quote

Wrong: echo "<h2 class=\"myH2\">hello</h2>";
Right: echo '<h2 class="myH2">hello</h2>';

String comparing:

* Returns 0 when equal.
Not case sensitive: strcmp (str1, str2);
Case sensitive: strcasecmp (str1, str2);

Concatination:

echo $my_str1 . "hello" . $my_str2;
echo $my_str1 . 3 . $my_str2;


Constants:
----------

* Constants are global.
ex. define("HELLO", "Hello world!");
echo HELLO; // outputs "Hello world."

Predefined constants:

__LINE__
__FILE__ 


Boolean operators:
------------------

AND, OR, XOR, NOR, NOT


Conditions:
-----------

if (...){ ... }
elseif (...){ ... }
else { ... }

switch (...) {
	case ... : ... break;
	default: ... ;
}

The ? Operator:
---------------

{expression} ? return_when_expression_true : return_when_expression_false;

Loops:
------

while ( ... ) { ... }
do { ... } while (...);
for (init_expression; test_expression; mod_expression) { ... }

break - will break out of the loop.
continue - skipps the current loop cycle.


Function default value:
-----------------------

function capitalize( $str, $each=TRUE )
{ ... }


Function referecnces:
---------------------

function foo(&$str) { ... }
foo(&$my_string);


Including and requiring PHP files:
----------------------------------

include('my_file.php');
include_once

require
require_once

* Require functions will halt execution if the required file doesn't exist.


PHP functions:
--------------

$exists=function_exists("my_function");


Classes:
--------

class A {
	var $m_var;

	A() {...} // ctor
	public function __construct() {...}	// php5 style constructor
	public function __destruct() {...}	// php5 style destructor
	function my_func() {$this->m_var = 10;}
}

$obj = new A();
obj->my_func();


Inheritance:
------------

calss B extends A {
	// The parent ctor won't be called automaticaly
	__construct() {parent::__construct();}

	// Overriding
	function my_func() {parent::my_func();}
}

:: operator
You can refer to class variables and methods instead of refering to instance variables and methods. Will affect all instances of that class.


References:
-----------

$str = "hello";
$ref = &$str; // ref points to the same mem as str


Arrays:
-------

php picks the lowest empty numeric index:
$weekdays[] = 'Monday'
$weekdays[] = 'Tuesday'

- Manual indexing:

$weekdays[0] = 'Monday'
$weekdays[1] = 'Tuesday'

- Init via php 'array' function:
$weekdays=array('Monday', 'Tuesday', 'Wednesday');

- Associative array (string indexed):
$shapes=array('Soda Can' => 'Cylinder',
                'Note Pad' => 'Rectangle',
                'Apple' => 'Sphere');

- Traversing associative array:
foreach ($shapes as $key => $value) {
    print"The $key is a $value.<br>\n";
}

- Validating the array:
$arr = array('val1', 'val2');
echo is_array($arr) ? 'a valid array' : 'not an array';

- Counting the array elements:
$cnt = count($arr);

- Sorting the array:
sort($arr, sort_regular);
sort($arr, sort_numeric);
sort($arr, sort_string);
sort($arr, sort_locale_string);

- Dumping all the array:
echo var_dump($arr);

- Extracting variables from an array:
(Generates local variables from name:val pairs)
extract($arr);

- To prevent "extract" of overiting vars with the same name:
extract($array, EXTR_PREFIX_ALL, "the_prefix");

- Building an array from variables:
(The complement to "extract")
$SodaCan='Cylinder';
$NotePad='Rectangle';
$arr = compact('SodaCan', 'Note Pad');

- Array functions:
Reset (array); - Resets the pointer to the beginning of the array.
array_push (array,elements); - Adds elements to the end of the array.
array_pop (array); - Returns and removes the last element of an array.
array_unshift (array,elements); - Adds elements to the beginning of the array.
array_shift (array); - Returns and removes the first element of an array.
array_merge (array,array); - Combines two arrays together and returns the new array.
array_keys (array); - Returns an array containing all of the keys from the supplied array.
array_values (array); - Returns an array containing all of the values from the supplied array.
Shuffle (array); - Resorts the array in random order.