Advance vs. basic

//Advance way

    smooth();
    noStroke();
    fill(0);
   int center=25;
   int xcircle = center;
   int ycircle = center;
   int radius = 50;
   for( int i = radius; i>0; i=i-5){
      xcircle = center;
      ycircle = center;
      radius = i;
      fill(radius);
   ellipse(xcircle,ycircle,radius,radius); )



vs 

//Not so advance way

    smooth();
    noStroke();
    fill(0);
   ellipse(25,25,50,50);
   ellipse(25,25,45,45);
   ellipse(25,25,40,40);
   ellipse(25,25,35,35);
   ellipse(25,25,30,30);
   ellipse(25,25,25,25);
   ellipse(25,25,20,20);
   ellipse(25,25,15,15);
   ellipse(25,25,10,10);
   ellipse(25,25,5,5);



It took me a whole morning to figure out how to use variable and loop in Processing. It had been very frustrating at the start but then thanks to the tutorial slides in the R drive and some of the tutorial video uploaded on Youtube, I started to figure out a little bit about these stuff. Still confusing and cannot apply to all the situation though.

To the tutors: If you happen to see this post, please correct the "advance way" code if i was wrong. And please tell me which parts are unnecessary. Thanks in advance.