《编程珠玑》翻转字符串算法

reverse.php

<?php
function reverse($arr, $len, $m){ 
    $k = 0; 
    for($i = 0; $i < $m; $i++){ 
        $k = 1;
        $temp = $arr[$i]; 
        while(($k*$m+$i) % $len != $i){ 
            $arr[($k-1)*$m+$i] = $arr[$k*$m+$i]; 
            $k++; 
        } 
        $arr[($k-1)*$m+$i] = $temp; 
    }
    return $arr;
}

Has php Notice about array offset