If "i+=0.5" is OK, why not "i+=1/2"?

naockovich

Say I want to draw 2 circles. One followed by another, both spreading out. To make the second circle come behind the first one, I'd use variable i,j like below. This one works as I expect, but when I writej+=1/2 instead of j+=0.5, it doesn't work. What's wrong with the a fraction?

    float i,j=0;

    void setup(){
      size(200,200);
    }
    void draw(){
      ellipse(width/2,height/2,i,i);
      ellipse(width/2,height/2,j,j);
      ++i;
      j+=0.5;
    }

TfGuy44

When you do math with ints, the result is an int. 1/2 is 0

When you do math with a float, the result is a float. 1/2.0 is 0.5

koogs

integer division...

http://forum.processing.org/two/discussion/6013/not-sure-why-this-happens-integer-division

(there used to be a FAQ for this, i'm sure. but i can't find one)

oh, here it is. it was mentioned above but has moved to github:

https://github.com/processing/processing/wiki/Troubleshooting#why-does-2--5--0-instead-of-04

GoToLoop

That is 1 of the most serious omissions for Processing's web reference for operator /: X(
https://Processing.org/reference/divide.html

There are only 2 examples there using int.
But no mention about the result is truncated when both operands are of whole type! 8-}

Remember that for a long time, ArrayList's reference didn't say a single word about generics & its diamond <>.
The result is that many folks still dunno about <> due to the long wait to include such important information! (:|

naockovich

Thank you. Now I understand why. This is what I'd never figure out by myself. You guys are so good at teaching :-bd