劈裂仅使用正则表达式

Question

preg_split('#(?=.)(?<=.)#u','asfaaasfdf');字符串为固定大小的块产生：

Array 
(
    [0] => a 
    [1] => s 
    [2] => f 
    [3] => a 
    [4] => a 
    [5] => a 
    [6] => s 
    [7] => f 
    [8] => d 
    [9] => f 
) 

我怎么只能改变正则表达式，并得到：

Array 
(
    [0] => as 
    [1] => fa 
    [2] => aa 
    [3] => sf 
    [4] => df 
) 

或：

Array 
(
    [0] => asf 
    [1] => aaa 
    [2] => sfd 
    [3] => f 
) 

Answer 1

为什么使用拆分？使用比赛：

preg_match_all('/.{1,3}/s', 'asfaaasfdf', $matches); 
print_r($matches[0]); 

输出：

Array 
(
    [0] => asf 
    [1] => aaa 
    [2] => sfd 
    [3] => f 
)