We can write our own program to sort array in PHP without using built in functions like – sort(), rsort().
Example
<?php $array = array(21, 9, 10, 11, 9); echo "Array Unsorted<br /?>"; print_r($array); for($i = 0; $ < count($array); $i ++) { for($j = 0; $j < count($array)-1; $j ++){ if($array[$j] > $array[$j+1]) { $temp = $array[$j+1]; $array[$j+1]=$array[$j]; $array[$j]=$temp; } } } echo "Array After Sorting: "; echo "<br/>"; print_r($array); ?>