PHP compare uploading with stored image!!!

[misxa]

How to do this?

I know that some will tell me to use md5_file function, but how?

[mrhappiness]

as described in the manual: http://www.php.net/md5-file

if (md5_file('file on server.ext') == md5_file($_FILES['name of input field']['tmp_name']))
  echo 'This file is already there';