It is very important to see how to increment variables as they relate to the loop variables will change the X location of a box. Note that the array variable is col since changing the X location moves the boxes to the right .... and thus changes the column.

Note that one wants to change this x location over 4 times. Since the loop is from 0 to 3, this makes col*width be

0 * width
1 * width
2 * width
3 * width
thus moving the X location over each time the loop comes back
Now, note where this is It should not be here since this will changing the Y location - which is related to the row variable. Note that the row variable is defined in the loop below this line in this example. This will not work.

What would it do?

Since row would by default be 0 here, row*height= 0, so it would make localY = initialBoxY
and thus there would only show up one row ... and it would be written over 4 times.