Clonefish comes with a powerful file input validation. You can set a file input to be mandatory (which is checked on the client side with JavaScript too!). Furthermore, you can check not only the filetypes (and channels (RGB/CMYK) for JPGs), but also the required minimum/maximum filesize. The maximum size is set to the upload_max_filesize PHP setting by default - quite comfortable!
The form also demonstrates the use of the 'binaryvalue' setting: that's why the methods of clonefish will return the (binary) contents of the file (in the test page you'll only see a note instead of the contents, since binary contents don't look nice in browsers - check the "Results of a $clonefish->getElementValues() call" section below after submission)

inputFile - mandatory JPEG RGB

click here to see how easy it is to create it!

Below are the dumps of some PHP variables - submit the form to see the changes!

Contents of the $_POST array:
$_POST = array (
)
      

Results of a $clonefish->getElementValues() call:
array (
  'inputfile1' => NULL,
  'id' => 'validfile',
)