PHP 正则表达式、反则轮换字符串

代码：

?

? //反则，保留除了A-Za-z0-9@\*的字符
??? $word = "[email protected]*5822?" ;
??? $par = array('/[^A-Za-z0-9@\*]/');?
??? $word = preg_replace($par, "", $word);
??? echo ??? $word;
??? echo "<br>";

??? //正则，剔除A-Za-z0-9@\*字符
??? $word = "[email protected]*5822?" ;
??? $par = array('/[A-Za-z0-9@\*]/');?
??? $word = preg_replace($par, "", $word);
??? echo ??? $word;

结果：

?

[email protected]*5822
-