Functions php array

• array_filter http://php.net/manual/fr/function.array-filter.php
  Allow to filter an array by a custom function that return the value to keep,
  and if no function is given, it'll filter out FALSE value ('' , FALSE , 0 , NULL)

• array_shift http://fr2.php.net/array_shift
  array_shift() shifts (remove) the first value of the array off and returns it, shortening the array by one element and moving everything down. All numerical array keys will be modified to start counting from zero while literal keys won't be touched. Return the shifted value.

• array_flip
  http://php.net/manual/en/function.array-flip.php
  Allow to flip an array so that value become key and vice-versa

$array = array(
 '1' => 'value1',
 '2' => 'value2',
);
$array_flipped = array_flip($array);
print_r($array_flipped);

$array array(
 'value1' => 1
 'value2' => 2 
);