PHP Random FIle Name Function

Its always recommended that you rename a file uploaded by users. If it is not done, there is a higher chance that a file of a similar name is already in your directory. To get a random name I have written the function.

//Its a good idea to rename the file uploded by the users so as to avoid an overwrite to a file.
//We need a random file name (to be generated on the fly) in case when we ask users to upload a file and ...
//we do not want to have a clash between file names
//this uses time stamp to have a unique name
//this function uses Microtime to ensures that file name is unique.
//this function can be called even in a for loop, then also it would return  unique Name

function randomFileName($month=0,$year=0,$random='random')
{
if(0==$month) $month=date('m');
if(0==$year)  $year='RFILE'.date('Y');
if('random'==$random) $random=time();//to create uniqueness
$date=date('MjGis');//to create uniqueness
$microtime=microtime(true);//to create uniqueness
$digitsAfterDecimal=substr($microtime,strpos($microtime,'.')+1);
$name=$year.$month.$random.$date.$digitsAfterDecimal;
return $name;
}