PHP文件上传的原理及实现

upload.html
<form enctype="multipart/form-data" action="upload.php" method="post">
<input type="hidden" name="max_file_size" value="100000">
<input name="userfile" type="file">　　
<input type="submit" value="上传文件">
</form>

upload.php
$f=&$HTTP_POST_FILES['Myfile'];
$dest_dir='uploads';//设定上传目录
$dest=$dest_dir.'/'.date("ymd")."_".$f['name'];//设置文件名为日期加上文件名避免重复
$r=move_uploaded_file($f['tmp_name'],$dest);
chmod($dest, 0755);//设定上传的文件的属性