php 读取文件头判断文件类型的实现代码

<?php $filename = "11.jpg";
//为图片的路径可以用d:/upload/11.jpg等绝对路径
$file = fopen($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: $fileType = png; break;
default: echounknown;
}
echo这是一个.$fileType. file:.$typeCode;

?>
//linux下php还有个函数可以判断文件类型
<?php
echo mime_content_type(11.gif) . "\n";
echo mime_content_type(22.php);
?>