use-revolution Digest, Vol 22, Issue 14

[Alex Tweedly]

Richard Gaskin wrote:

>
> Since each pass through the loop involves checking for the same number 
> of steps (4), could a stop option in the repeat statement be helpful?
>
step option ?  That might help a bit -

I'm not quite sure how you'd add a "step" option to the "repeat for each 
char" form (nb we need to access almost every character,  not just every 
fourth one).  I guess you could invent some syntax like

repeat for each 4 chars (c1,c2,c3,c4) in the imageData of img "image"
   add 1 to histo[chartonum(c2) + chartonum(c3) + chartonum(c4)]
end repeat

at a (very) rough count, that could maybe save 50% !!

N loop repeats / tests
4N char assignments
3N retrieves
2N additions
N array lookups
N additions

versus

>  repeat for each char c in lImageData
>     add chartonum(c) to temp
>     add 1 to count
>     if count = 4 then
>         add 1 to histo[temp]
>     end if
>     put 0 into temp
>     put 0 into count
>   end repeat

4N loop repeats / test
4N char assignments
4N additions
4N tests
N array lookups
N additions
4N assignments
4N assignments


So I think the addition of a "step" option to the "repeat for each" form 
of loop would be worthwhile - and I hope someone can come up with a 
better syntax than I used above !!

-- 
Alex Tweedly       http://www.tweedly.net



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