note TheDamian <blockquote><i> I'm not even sure what the advantage might be to using the same filename for input and output. </i></blockquote> I certainly don't suggest (either here or in the book) that you <em>should</em> use the same file for input and output. I merely observe that, if you allow people to independently specify input and output filenames on the command-line, some of them inevitably <em>will</em> use the same name for both files (either intentionally or accidentally). So you have to be aware of the possibility and cope with it somehow. <p>In the book, I suggest two solutions, one of which is more efficient but apparently fails on certain obscure operating systems (and, yes, I will definitely update the book to reflect that limitation, as soon as I can). 488824 488836