My output has a "?" on the name and the file doesn't open anymore

<?php
error_reporting(E_ALL);
ini_set('display_errors' ,1);

//expression to be found in file name
$find = '.5010.';

//directory name
//we will store renamed files here
$dirname = '5010';
if(!is_dir($dirname))
    mkdir($dirname, 0777);

//read all files from a directory
//skip directories
$directory_with_files = './';
$dh  = opendir($directory_with_files);
$files = array();
while (false !== ($filename = readdir($dh)))
{
    if(in_array($filename, array('.', '..')) || is_dir($filename))
        continue;

    $files[] = $filename;
}

//iterate collected files
foreach($files as $file)
{
    //check if file name is matching $find
    if(stripos($file, $find) !== false)
    {

        //open file
        $handle = fopen($file, "r");
        if ($handle)
        {
            //read file, line by line
            while (($line = fgets($handle)) !== false)
            {

                //find REF line
                        $refid = 'REF*2U*';
                        if(stripos($line, $refid) !== false)
                              {
                              //glue refernce numbers
                              //check if reference number is not empty
                              
                              $refnumber = str_replace(array($refid, '~'), array('', ''), $line);
                        if($refnumber != '')
                              {
                        $refnumber = '_'. $refnumber .'_';

                        $filerenamed = str_replace($find, $refnumber, $file);
                              copy($file, $dirname . '/' . $filerenamed);
                                    }

                        echo $refnumber . "\n";
                              }
            }

            //close file
            fclose($handle);
        }
    }
}