将邮箱地址的第3 位到'@'之间的字符串替换为符号'*' 谢谢
echo preg_replace('/(?<=.{3}).+@/', '*@', 'username@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);
