let char_of_line file n =
let ic = open_in file in
let rec iter acc l =
if l >= n then
acc
else
match
try Some (String.length (input_line ic))
with End_of_file -> None
with
None -> acc
| Some n -> iter (acc+n+1) (l+1) (* acc+n+1 for the newline character *)
in
let n = iter 0 0 in
close_in ic;
n