Increment bug in repeat loops

[Jacques Hausser]

Le 21 nov. 2009 à 05:13, stephen barncard a écrit :

> but it works if you set the numberformat  to match


Yes Stephen, if the computation stays inside the loop, but not for the computation on the counter itself ! Try

on mouseUp
   put "" into fld "Result"
   set the numberformat to "#.##################"
   repeat with i = 0 to 1 step 0.1
      put i & return after fld "Result"
   end repeat
   set the numberformat to "#.#"
   repeat with i = 0 to 1 step 0.1
      put i & return after fld "Result"
   end repeat
end mouseUp

One step too much in each loop ! The 12th and last one gives 1.099999999999999867 for the first loop, 1.1 for the second one.

I guessed it is because the counter computation and test are never subject to computation (outside the repeat process) and put into a container, so the numberformat has no effect on it. I tried to modify i inside the second loop:

set the numberformat to "#.#"
repeat with i = 0 to 1 step 0.1
   put i + 1 - 1 into dummy
   put dummy & return after field "Result"
   put dummy into i
end repeat

and with this solution it works as expected, 11 steps, the last one giving 1 ! But still, it is usually better to limit counter and increment to integers...

Happy WE

Jacques

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Prof. Jacques Hausser
Department of Ecology and Evolution
Biophore / Sorge
University of Lausanne
CH 1015 Lausanne
please use my private address:
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E-Mail:	jacques.hausser at unil.ch
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