in fun2(++n) , let take fun2(3) , value of n=3 and its ++n so first update the value of n , become n=4 and then passed as fun1(4)
but in fun2(n++) , let take same example fun2(3) , value of n=3 and its n++ so first passed value as fun1(3) then change value of n=4
( here n is local variable )