infinite for loop problem

Code:

---

package
{
        import flash.geom.*;
        import flash.display.*;
        import flash.events.*;
       
        public class Main extends MovieClip
        {
                var sp:Sprite = new Sprite();
               
                public function Main()
                {        addChild(sp);               
                        drawPoints(20,20);
                }
               
                public function drawPoints(sx=0,sy=0)
                {
                        var ptArr = [0,0,10,0,10,10,10,20,60,20,60,10,60,0,70,0];
                        sp.graphics.lineStyle(1,0x00ff00);
                        sp.graphics.moveTo(sx,sy);
                        for(var i=2;i<ptArr.length;i+2)  <--PROBLEM PORTION
                        {
                                sp.graphics.lineTo(ptArr[i]+sx,ptArr[i+1]+sy);
                                trace(i);
                        }
                }
        }
}

---

When I run the code, it seems to run eternally and freeze, however in the for loop, if I replace i+2 with i++ and put in another i++ inside, the problem doesn't occur.....any idea what's going on?

When using i+2, you aren't actually assigning the value (while i++ translates to i = i + 1).

So try instead i += 2 or i = i + 2.

oh....thanks....