On Nov 9, 2010, at 12:32 PM, Peter Breitsprecher wrote: > Ok, here is the code I have written so far for the function I am having > trouble with... > > (define (rep-loop) > (newline) > (display "repl>") > (read-token))
I'm going to ignore rep-loop. > > (define (read-token) > (let ((expr (read-char))) > ((cond [(char-whitespace? expr) (read-token1)] > [(eq? expr #\() (read-token2)] > [(eq? expr #\)) (read-token3)] > [(char-alphabetic? expr) (read-token4)] > [(char-numeric? expr) (read-token5)] > [else (display "Exiting Loop")])))) Okay! we've got a name: read-token. The way it's written, it's going to be very hard to test. This is because it operates on typed-in input. This program would be much easier to develop if you could write a function that accepts strings as input. Can we break the problem up this way? John Clements > The cond calls other functions I have written just so I could see it if was > reading the output letter by letter... Now I need to make read-token read > the whole word if it sees a character and the entire number if it sees a > number. > > Is that getting closer? > > On 9 November 2010 15:28, John Clements <cleme...@brinckerhoff.org> wrote: > > On Nov 9, 2010, at 12:27 PM, Peter Breitsprecher wrote: > > > I'd lie but no.. I was just trying to clarify what I was looking for. I > > gave a the code for one of the functions I had written, and then an example > > of the input the user is giving below, and then tried to describe in more > > detail what I needed help with... > > Well, I'm glad you're not lying :). > > Can you start by picking a name for the function that you're trying to write? > > John Clements > > > > On 9 November 2010 15:23, Shriram Krishnamurthi <s...@cs.brown.edu> wrote: > > Hi, > > > > That would not be considered an "example" for at least two reasons. Do you > > see why? > > > > > >> On Nov 9, 2010 12:17 PM, "Peter Breitsprecher" <pkbre...@lakeheadu.ca> > >> wrote: > >> > >> As an example, I want have most of the functions for Plus, Minus already > >> written. > >> > >> Here is the code for it. > >> > >> (define (plus num1 num2) > >> (+ num1 num2)) > >> > >> That is childs stuff... Here is where I am having the problem, and please > >> keep in mind I am new to DrRacket... > >> > >> If my program accepts input such as > >> (plus 13 5) > >> > >> I need to parse it so that I know what it is asking for. If It is a left > >> parent, then I need to move on, if it is a right parent, move on to the > >> next character, once i get to the next character I can see it is an > >> alphanumeric character, but then I need to somehow read the whole word, so > >> that I can store that value in a variable so that I can read the next > >> number. If the numbers are single digits, it is easy, because they are > >> only one charater each and read-char works perfect, but I need something > >> like a read-word, or read-number and I can't seem to figure out how to do > >> it. > >> > >> So really I need to know how do I read the words when there are characters > >> present, and read the whole numbers when there is a number present. > >> > >> > >> > >> On 9 November 2010 15:00, John Clements <cleme...@brinckerhoff.org> wrote: > >> > > >> > > >> > On Nov 9, 2010, a... > >> > >> -- > >> Kurt Breitsprecher > >> (807) 474-9601 > >> pkbre...@lakeheadu.ca > >> > >> > >> _________________________________________________ > >> For list-related administrative tasks: > >> http://lists.racket-lang.org/listinfo/users > > > > > > > > -- > > Kurt Breitsprecher > > (807) 474-9601 > > pkbre...@lakeheadu.ca > > > > > > > -- > Kurt Breitsprecher > (807) 474-9601 > pkbre...@lakeheadu.ca >
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