将邮箱地址的第3 位到'@'之间的字符串替换为符号'*' 谢谢
回复讨论(解决方案) echo preg_replace('/(?<=.{3}).+@/', '*@', 'username@mail.net');
use*@mail.net
$str =12q2345qqqq667@qq.com;$sub = substr($str, 2,strpos($str,'@') -2);$len = strlen($sub);$replacestr = str_repeat('*',$len);$newstr = str_replace($sub, $replacestr, $str);var_dump($newstr);