FILENAME = this / is (your, file.name.JPG
$basename=basename($_FILES['Filedata']['name']);
$filename=pathinfo($basename,PATHINFO_FILENAME);
$ext=pathinfo($basename,PATHINFO_EXTENSION);
//replace all these characters with an hyphen
$repar=array(".",","," ",";","'","\\","\"","/","(",")","?");
$repairedfilename=str_replace($repar,"-",$filename);
$cleanfilename=$repairedfilename.".".strtolower($ext);
RESULT = this-is-your-file-name.jpg