[racket] Basic inquiry

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 <dyoo at cs.wpi.edu> wrote:
> On Fri, Apr 27, 2012 at 11:27 AM, saad bashir <bashir.saad at 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