[php] filemtime "warning stat failed for"

I already read it so many questions and answers about it but I can't still solve my problem...

I'm trying to create a function that deletes all the files with "xml" or "xsl" extension that has been created one day ago. But I'm getting this warning on each file I have:

Warning: filemtime() [function.filemtime]: stat failed for post_1003463425.xml in /home/u188867248/public_html/ampc/library.php on line 44

All the files of this directory have the same structure name "post_ + randomNum + .xml" (example: post_1003463425.xml or post_1456463425.xsl). So I think it's not an encoded problem (like I saw in other questions).

The code of my function is this:

 function deleteOldFiles(){
    if ($handle = opendir('./xml')) {
        while (false !== ($file = readdir($handle))) { 

            if(preg_match("/^.*\.(xml|xsl)$/i", $file)){

                $filelastmodified = filemtime($file);

                if ( (time()-$filelastmodified ) > 24*3600){
                    unlink($file);
                }
            }
        }
        closedir($handle); 
    }
}

Thanks for your help :)

Shorter version for those who like short code:

// usage: deleteOldFiles("./xml", "xml,xsl", 24 * 3600)


function deleteOldFiles($dir, $patterns = "*", int $timeout = 3600) {

    // $dir is directory, $patterns is file types e.g. "txt,xls", $timeout is max age

    foreach (glob($dir."/*"."{{$patterns}}",GLOB_BRACE) as $f) { 

        if (is_writable($f) && filemtime($f) < (time() - $timeout))
            unlink($f);

    }

}

in my case it was not related to the path or filename. If filemtime(), fileatime() or filectime() don't work, try stat().

$filedate = date_create(date("Y-m-d", filectime($file)));

becomes

$stat = stat($directory.$file);
$filedate = date_create(date("Y-m-d", $stat['ctime']));

that worked for me.

Complete snippet for deleting files by number of days:

$directory = $_SERVER['DOCUMENT_ROOT'].'/directory/';
$files = array_slice(scandir($directory), 2);
foreach($files as $file)
{
    $extension      = substr($file, -3, 3); 
    if ($extension == 'jpg') // in case you only want specific files deleted
    {
        $stat = stat($directory.$file);
        $filedate = date_create(date("Y-m-d", $stat['ctime']));
        $today = date_create(date("Y-m-d"));
        $days = date_diff($filedate, $today, true);
        if ($days->days > 1) 
        { 
            unlink($directory.$file);
        }
    } 
}

For me the filename involved was appended with a querystring, which this function didn't like.

$path = 'path/to/my/file.js?v=2'

Solution was to chop that off first:

$path = preg_replace('/\?v=[\d]+$/', '', $path);
$fileTime = filemtime($path);