原始代码：我刚刚添加了
$len一部分。
<?php // function to generate and print all N! permutations of $str. (N = strlen($str)).function permute($str,$i,$n,$len) { global $ret; if ($i == $n){ if(in_array(substr($str,0,$len),$ret)==false){$ret[]=substr($str,0,$len);} }else { for ($j = $i; $j < $n; $j++) { swap($str,$i,$j); permute($str, $i+1, $n, $len); swap($str,$i,$j); // backtrack. } }}// function to swap the char at pos $i and $j of $str.function swap(&$str,$i,$j) { $temp = $str[$i]; $str[$i] = $str[$j]; $str[$j] = $temp;}$ret = array();$str = "123456";permute($str,0,strlen($str), 3); // call the function.print_r($ret);?>
