array_filter() function in php

array_filter() function of PHP is used to filter the values of an array with the help of a user define function or callback function. It is an inbuilt function of PHP.

Syntax:

Here

1. $array_name is the array which values we want to filter.
2. $callback function is a user define function.it returns either TRUE or FALSE. If it returns TRUE then the value is added in resultant array. It is not mandatory.
3. $flag_param is used to specify the arguments in callback function. It has two values. If the value is ARRAY_FILTER_USE_KEY then it takes only keys as arguments but if the value is ARRAY_FILTER_USE_BOTH then it use both keys and values of array to filter the values. It is not mandatory.

Example:

<?php
/* this example filter odd elements of an array */
function cal_odd($arr)
{
   if($arr%2!=0)
     return TRUE;
   else
     return FALSE;
}
$arr1= array(1,2,3,4,5,6,7,8,9);
$result=array_filter($arr1,"cal_odd");
echo "<pre>";
print_r($result);
?>

Output: