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Today we will re-visit Greenfoot's
We'll work on labs individually today, not with partners.
Hint: If you look near the top ofYou can recall the loops we wrote in yesterday's lecture.class Turtle , you can see that there is a field to keep track of eachTurtle 's direction.
Stopping when the internal angle was (360-15)° or more was kind of a yucky end-condition; initially did that because angles “wrap around” back to 0°, and we don't have a good way of telling 1° from 361°, so we needed to stop before we reached 360°.
stopping when the turtle is facing (nearly) east is also incorrect for another reason: it only draws a full circle if the turtle started by facing east. But clearly, it makes sense to make a full revolution no matter what direction the turtle starts in.
However, we can tell from the outset how many rotations we want to make: 360°/15°. And since we're now using an index variable, we can change our loop to say “do the following 24 times”. Modify your program accordingly: change the loop's ending condition so that it stops once it's made the appropriate number of turns (rather than checking its current angle).
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©2010, Ian Barland, Radford University Last modified 2010.Oct.28 (Thu) |
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