$newfile = "0001";  # Initialize to 0001
++$newfile;         # Now contains 0002

##</code><code>##

$newfile = "0001";                       # Initialize to 0001
$newfile = sprintf("%04d", $newfile+1);  # Now contains 0002

##</code><code>##

$newfile = "0001";  # Initialzie to 0001
$newfile += 1;      # Now contains 2