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
