Q:

Code with i+= in the loop is not working

I have the following piece of code called Code1.
http://pastebin.com/tc0Vd8xh
When I run this, the sketch does not work.
However when I replace "i=+50" for "i = i + 50" the code works. 
My question is why the "i=+50" bit does not work? 
As far as I know "i=+50" is proper Java and Processing is based on Java. 
I tried to Google about "i=+50" but Google does not process non-alphanumeric characters. 
So I came here and I searched in previous questions before asking here. Anyone, any idea why "i=+50" does not work?

A:

You're using =+, which is not a java operator (or an operator in any other language I know of)
The proper syntax is:
i+=50

