求一个PHP正则

Question

试试: ^[a-z](_?([a-z\d]+_)*[a-z\d])?$未测试!

Answer 1

测试了一下, 应该这样: /^[a-z](_?([a-z\d]+_)*[a-z\d]+)?$/
--------------<?php$str_arr = array(
'a_fda_43',
'fdsafda',
'432423',
'fdwq4i23',
'_fdrew',
'_fdsa_fdsa',
'fda__fd',
'432fdsa',
'fds423_',
'dfs_f_fd_');$pattern = "/^[a-z](_?([a-z\d]+_)*[a-z\d]+)?$/i";foreach ($str_arr as $value)
{
if (preg_match($pattern, $value))
echo "{$value}: yes<br />";
else
echo "{$value}: no<br />";
}?>