A simple implementation of Merge Sort in PHP

MergeSort.php

<?php


function mergeSort($array) {

    if( sizeof($array) == 1 ) return $array;
    $middle = floor(sizeof($array) / 2);
    $l_arr = mergeSort( array_slice( $array, 0, $middle));
    $r_arr = mergeSort( array_slice( $array, $middle));
    $l_ptr = $r_ptr = $d_ptr = 0;
    $result = array();

    while($d_ptr < sizeof($array)) {

        if( $l_ptr == sizeof($l_arr) ) {
            $result[$d_ptr] = $r_arr[$r_ptr];
            $r_ptr++;
        }
        else if( $r_ptr == sizeof($r_arr)) {
            $result[$d_ptr] = $l_arr[$l_ptr];
            $l_ptr++;
        }
        else if( $l_arr[$l_ptr] < $r_arr[$r_ptr] ) {
            $result[$d_ptr] = $l_arr[$l_ptr];
            $l_ptr++;
        }
        else {
            $result[$d_ptr] = $r_arr[$r_ptr];
            $r_ptr++;
        }

        $d_ptr++;
    }

    return $result;



}


$arr = array(3,5,1,2,8,7,6,9,4);

echo implode(',', mergeSort($arr));