php遞迴刪除目錄所有檔案

<meta http-equiv="content-type" content="text/html; charset=gb2312">

<?php
function tree($directory)
{
$mydir=dir($directory);
echo "<ul> ";
while($file=$mydir->read()){
if((is_dir("$directory/$file")) and ($file!=".") and ($file!=".."))
{echo "<li><font color="#ff00cc"><b>$file</b></font></li> ";
tree("$directory/$file");
}
else{
    $a = explode('.',$file);
    if($a[1] == 'html' || $a[1] == 'htm')
   {
        //unlink($file);
            echo "<li>$file</li> ";
        }   
   

}
}
echo "</ul> ";
$mydir->close();
}
//開始運行

echo "<h2>目錄為粉紅色</h2><br> ";
tree("./");
?>