LOGO-L> Inverting Numbers

["Olga Tuzova" <olgatu@ort.spb.ru>]

Hello everybody,

I'd like to introduce you to some rather interesting examples 
proposed by teachers S.Gorlitskaya and I.Kuznetsova from 
St.Petersburg and posted in Russian newspaper "Informatics".
I think these examples are in time for our "word games".

Here are  the first ones. 

The main procedure reads a number as a word.
how_digits? counts the "sensible" digits of the number.
Then invert calls inverty, which returns the  inverted number.

I've slightly changed the initial code, and if there is something 
wrong here, it's my fault.
---------------------------------
to how_digits? :n
;counts the "sensible"(?) digits of the number 
if emptyp :n [op 0] 
ifelse not (first :n)=0[op count :n]~
                       [op how_digits? butfirst :n] 
end

to invert :n 
op inverty how_digits? :n :n 0
end

to inverty :k :n :new_n
; inverts the initial number :n and returnes it as :new_n
if :k=0 [op :new_n]
op inverty :k-1 int :n/10 10*:new_n+remainder :n 10  
end

to main
pr [input any number, it may begin with 0  ==>]
pr  invert rw
end
------------------------------------------------------
 
Regards,
Olga.
---------------------------------------------------------------
Please post messages to the Logo forum to logo-l@gsn.org.  Mail
questions about the list administration to logofdn@gsn.org.  To
unsubscribe send    unsubscribe logo-l    to majordomo@gsn.org.