Hi Saad, I don't know if this is advisable in general, and hopefully I'm not making a rookie teacher mistake here, but it seems that in your case you could use some videos to get you started with the basics: For example: http://www.youtube.com/watch?v=IwpnDJ45yLA
There might be some little differences with the current version of DrRacket though. Other videos: http://www.youtube.com/results?q=drracket This should help you start a little. After that, for the programming part, it's probably better if you stick to HtDP. Cheers, Laurent On Sat, May 12, 2012 at 2:35 PM, saad bashir <bashir.s...@gmail.com> wrote: > Dear Matthias, > > Thank you for replying to me. I am sure this is laughably basic for you. > > I got what you wrote. I know string-ith extracts the letter. My question > is how to use it. I have tried various ways of writing both in the def and > interaction sections but have not worked out. Even consulting the Helpdesk > has not helped as it does not tell me how to use the fucntion. > > Sorry if I am being very thick. I really want to do it right. > > Saad > > > On Fri, May 11, 2012 at 11:47 PM, Matthias Felleisen <matth...@ccs.neu.edu > > wrote: > >> >> The beginning of section 2.1.3 looks like this: >> >> >> > All other operations concerning strings consume or produce data other >> than strings. Here are some examples: >> > • string-length consumes a string and produces a (natural) number; >> > >> > • string-ith consumes a string s and extracts the one-character >> substring located at the ith position (counting from 0); and >> > >> > • number->string consumes a number and produces a string. >> > >> > Also look up substring and find out what it does. >> >> Which function do you think extracts a "letter" from a string? [[You can >> follow the links for the function names. Perhaps it is easier to read the >> docs.]] >> >> -- Matthias >> >> >> >> >> On May 11, 2012, at 4:22 PM, saad bashir wrote: >> >> > I am back again. I had a basic inquiry and your help got me started. >> > >> > My problem is as follows: >> > >> > I have just started to work through 2Htdp (i.e. the second edition) >> that you had guided me to. Having gone through the prologue I am now on the >> second chapter, "Fixed-size data." But have got stuck almost at the start. >> I have successfully done the first two exercises but have hit a road block >> on exercise 3 (section 2.1.3 "Mixing it up"). I do not know what >> instruction to use to insert or extract a letter from the ith position. I >> think I am doing something wrong when trying to look up things in Helpdesk. >> Please help. >> > >> > Saad >> > >> > On Fri, Apr 27, 2012 at 8:32 PM, Danny Yoo <d...@cs.wpi.edu> wrote: >> > On Fri, Apr 27, 2012 at 11:27 AM, saad bashir <bashir.s...@gmail.com> >> wrote: >> > > Your help was great. Things are working now. And a great thank you >> for >> > > leading me to the 2d edition of How to Design Programs. I had not >> known >> > > about it. >> > >> > >> > Glad to hear that it's working for you now! Please feel free to >> > continue to ask questions on the mailing list; we'll be happy to help. >> > >> > ____________________ >> > Racket Users list: >> > http://lists.racket-lang.org/users >> >> > > ____________________ > Racket Users list: > http://lists.racket-lang.org/users > >
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