php 正則去除中文，漢字，特殊字符

 正則去除中文，漢字，特殊字符：

$str = '  432.65456787rewqrewq6我的撒    ';
$ddd = "/[ ',:;*?~`!@#$%^&+=)(<>{}]|\]|\[|\/|\\\|\"|\|/";
$cc = '/[\x80-\xff]{0,}/';
$qq = "/[a-zA-Z]+/";
$str = preg_replace($ddd,'',$str);
$str = preg_replace($qq,'',$str);
$str = preg_replace($cc,'',$str);
echo $str;