Op 6-4-2012 15:23, Stephen Bloch schreef:
On Apr 6, 2012, at 3:39 AM, Roelof Wobben wrote:
;interp. (make-editorst)means the text in the editor is
;(string-append
<http://docs.racket-lang.org/htdp-langs/beginner.html#%28def._%28lib._htdp-beginner..rkt._lang%29._%28%28lib._lang%2Fhtdp-beginner..rkt%29._string-append%29%29>st)with
the cursor displayed between sand t
So for aaaaaaa| s has the value of aaaaa en t has the value of ""
No, s should be "aaaaaaa" and t should be "".
For aaaa|aaaa s I think s has the value of aaaaa and t has the value
of aaa
No, s should be "aaaa" and t should be "aaaa". The cursor is supposed
to be displayed between s and t.
If I use the length of the first string and I press one time on the
left-key then the new-length could be the old-one - 1. Then I could
use substring to cut that part away.
Sure. Note that you'll need to not only make the new s shorter than
the old s, but also make the new t longer than the old t. And vice
versa when somebody presses on the right-arrow key.
The t part I could say if it's empty substring ( s , (string-lenght
s), 1) and if it's not empty use a string-append.
You could, but that's unnecessarily complicated. string-append works
regardless of whether s or t is empty.
Stephen Bloch
sbl...@adelphi.edu <mailto:sbl...@adelphi.edu>
Thanks,
I now know I have a idea which could work.
Roelof
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