浅谈 PHP递归的理解（递归听起来很高端的词汇 其实就是两次循环）

$data = [ ???[‘pid‘=>0,‘id‘=>1], ???[‘pid‘=>1,‘id‘=>2], ???[‘pid‘=>3,‘id‘=>4], ???[‘pid‘=>0,‘id‘=>3],];
//对上面的数据进行递归排序(原生的写法)function genCate( $data, $pid = 0){ ???static $result = array(); ???foreach ($data as $key => $row) { ???????if ($row[‘pid‘] == $pid) { ???????????$result[] = $row;
 ???????????$parent_id = $row[‘id‘]; ???????????foreach($data as $v){ ???????????????if ($v[‘pid‘] == $parent_id) { ???????????????????$result[] = $v; ???????????????} ???????????}
 ???????} ???} ???return $result;}

PHP递归的写法

function genCate( $data, $pid = 0){ ???static $result = array(); ???foreach ($data as $key => $row) { ???????if ($row[‘pid‘] == $pid) { ???????????$result[] = $row; ??????????// $parent_id = $row[‘id‘]; ???????????genCate($data, $row[‘id‘]); ??????????/* foreach($data as $v){ ???????????????if ($v[‘pid‘] == $parent_id) { ???????????????????$result[] = $v; ???????????????} ???????????}*/ ???????} ???} ???return $result;}

　　其实就是同一个数组两次循环 通过变动的是父id 不断找子元素