PHP 文件类型判断代码

<？php
$filename = "D:\296.mid";
$file = fopen（$filename, "rb"）;
$bin = fread（$file, 2）; //只读2字节
fclose（$file）;
$strInfo = @unpack（"c2chars", $bin）;
$typeCode = intval（$strInfo["chars1"].$strInfo["chars2"]）;
$fileType = "";
switch （$typeCode）
{
case 7790:
$fileType = "exe";
break;
case 7784:
$fileType = "midi";
break;
case 8297:
$fileType = "rar";
break;
case 255216:
$fileType = "jpg";
break;
case 7173:
$fileType = "gif";
break;
case 6677:
$fileType = "bmp";
break;
case 13780:
$fileType = "png";
break;
default:
echo "unknown";
}
echo "this is a（an） ".$fileType." file:".$typeCode;
？>