Thank you all for the suggestions, it was indeed the .txt extension. Now I was able to run the program, however the results were not separated, they were all in just one line. But I'm not going to worry about that. Also thank you for suggesting the other resources, but so far I like the HtDP and I do not mind math. Actually I think it is nice... :-) Jakub Hadam <a href="mailto:jakub.hadam@gmail.com" target="_blank">jakub.hadam@gmail.com</a> <div class="gmail_quote">On Mon, Nov 21, 2011 at 10:01 PM, Stephen Bloch <<a href="mailto:sbloch@adelphi.edu" target="_blank">sbloch@adelphi.edu</a>> wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> <div> On Nov 21, 2011, at 3:35 PM, Todd O'Bryan wrote: > This is just a guess, but perhaps Windows has helpfully added a ".txt" > extension (or some other nonsense) to the end of your filename? You > might try looking at the file's properties, just to make sure > something weird isn't going on. </div>Or just un-checking "Hide extensions for known types" (which is usually the first thing I do when I sit down at a strange Windows machine). <div> > On another note, as long as your Fahrenheit->Celsius function works, > don't worry so much about the convert-file interface. That's basically > one of the "bells and whistles" that HtDP included to get students > excited. The latest versions of the curriculum have much flashier > stuff and once you get through about Chapter 20 or so, you can look up > how to access files directly without using a teachpack. </div>Speaking of "latest versions of the curriculum", I think most of us would recommend stopping before chapter 6 of HtDP (in fact, you could stop now) and switching to either Picturing Programs (<a href="http://www.picturingprograms.org" target="_blank">http://www.picturingprograms.org</a>) or HtDP Second Edition (<a href="http://www.ccs.neu.edu/home/matthias/HtDP2e/" target="_blank">http://www.ccs.neu.edu/home/matthias/HtDP2e/</a>). Both of these take a more graphics-based approach which we have found works better with most of our students. Picturing Programs starts with graphics from the very beginning, postponing arithmetic until after you've done some event-driven GUI programs, while HtDP2e does some numeric examples at the beginning but starts doing graphics and GUI very soon thereafter. Stephen Bloch <a href="mailto:sbloch@adelphi.edu" target="_blank">sbloch@adelphi.edu</a> </blockquote></div>