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                                 array_filter

   (PHP 4 >= 4.0.6)
   array_filter --  Filters elements of an array using a callback
   function

Description

   array array_filter ( array input [, callback callback])

   array_filter() iterates over each value in the input array passing
   them to the callback function. If the callback function returns true,
   the current value from input is returned into the result array. Array
   keys are preserved.

   Example 1. array_filter() example
   <?php
   function odd($var) {
       return($var % 2 == 1);
   }
   function even($var) {
       return($var % 2 == 0);
   }
   $array1 = array("a"=>1, "b"=>2, "c"=>3, "d"=>4, "e"=>5);
   $array2 = array(6, 7, 8, 9, 10, 11, 12);
   echo "Odd :\n";
   print_r(array_filter($array1, "odd"));
   echo "Even:\n";
   print_r(array_filter($array2, "even"));
   ?>

   The printout of the program above will be:
   Odd :
   Array
   (
       [a] => 1
       [c] => 3
       [e] => 5
   )
   Even:
   Array
   (
       [0] => 6
       [2] => 8
       [4] => 10
       [6] => 12
   )

   Users may not change the array itself from the callback function. e.g.
   Add/delete an element, unset the array that array_filter() is applied
   to. If the array is changed, the behavior of this function is
   undefined.

   If the callback function is not supplied, array_filter() will remove
   all the entries of input that are equal to FALSE. See converting to
   boolean for more information.

   Example 2. array_filter() without callback
   <?php
   $entry = array(
                0 => 'foo',
                1 => false,
                2 => -1,
                3 => null,
                4 => ''
             );
   print_r(array_filter($entry));
   ?>

   This will output :
Array
(
    [0] => foo
    [2] => -1
)

   See also array_map(), array_reduce(), and array_walk().
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