java for loop pre-increment vs post-increment

Question

Possible Duplicate:
Why doesn’t changing the pre to the post increment at the iteration part of a for loop make a difference?

for (int i = 0; i < 3; ++i)
   System.out.print(i + ".."); //prints 0..1..2


for (int i = 0; i < 3; i++)
   System.out.print(i + ".."); //prints 0..1..2

So what is the difference? in what cases can the pre-increment be used wrongly or by mistake which causes a bug...