php正则怎么隐藏部分邮箱

<?php
 //用户名、邮箱、手机账号中间字符串以*隐藏
function hideStr($str) {
  if (strpos($str, &#39;@&#39;)) {
    $email_array = explode("@", $str);
    //邮箱前缀
    $prevfix = (strlen($email_array[0]) < 4) ? "" : substr($str, 0, 3); 
    $count = 0;
    $str = preg_replace(&#39;/([\d\w+_-]{0,100})@/&#39;, &#39;***@&#39;, $str, -1, $count);
    $rs = $prevfix . $str;
  } else {
    //正则手机号
    $pattern = &#39;/(1[3458]{1}[0-9])[0-9]{4}([0-9]{4})/i&#39;;
    if (preg_match($pattern, $str)) {
      $rs = preg_replace($pattern, &#39;$1****$2&#39;, $str); // substr_replace($name,&#39;****&#39;,3,4);
    } else {
      $rs = substr($str, 0, 3) . "***" . substr($str, -1);
    }
  }
  return $rs;
}
?>
<?php
$account = "baidu.com";
$email = "123456@qq.com";
$phone = "15999888888";
?>