#for i = 0 to 9 do
   print_int i
 done;;
0123456789- : unit = ()
#let v=[|1;2;3|];;
v : int vect = [|1; 2; 3|]
#v.(2);;
- : int = 3
#for i = 0 to vect_length v-1 do
   print_int v.(i)
 done;;
123- : unit = ()
#let i = ref 0 in
 while !i < vect_length v do
    print_int v.(!i); incr i
 done;;
123- : unit = ()