1 <?php 
 2     $a=[
 3 
 4         ‘a‘=>[‘d‘=>[‘aa‘=>1,‘bb‘=>2,‘cc‘=>3]],
 5         ‘b‘=>[‘f‘=>[‘dd‘=>4,‘ee‘=>5,‘ff‘=>6]],
 6         ‘c‘=>[‘g‘=>[‘gg‘=>7,‘hh‘=>8,‘ii‘=>9]],
 7         ];
 8 
 9         
10         $b=reduce_arr($a);
11         echo ‘<pre>‘;
12         var_dump($b);
13 
14 
15  function reduce_arr ($arr) {
16 
17         static $temp = array(); // 声明了一个静态局部变量
18 
19         foreach ($arr as $key => $val) {
20             if (is_array($val)) {
21                 reduce_arr($val);
22             } else {
23                 $temp[$key] = $val;
24             }
25         }
26         return $temp;
27 }
28  ?>