There are no state laws that govern pocket knives that clip in your pocket and there are no blade length laws. Basically, the only knife laws in Indiana are automatic (switch blades) and throwing stars are illegal. That being said, if you were on private property you have to obey their requests/rules or they can ask you to leave.
Ah, I miss the good ole days when I could buy Switchblades, Stars and Balisongs at the Mall...when I was 13..