<?php

$subject = "my email is [email protected]";

//在這里補充代碼，實現正則匹配，并輸出郵箱地址

$P='/my\s+email\s+is\s+(\w+@\w+\.\w+)/';（\s不是表示空字符嗎啊換這種寫法也是錯的啊'/my email is (【\w+】@\w+\.\w+)/'）為什么啊

preg_match($p, $subject, $matches);

echo $matches[1];

為什么會報錯??？Notice: Undefined variable: p in /26/562/J3c4/index.php on line 5

Warning: preg_match(): Empty regular expression in /26/562/J3c4/index.php on line 5