(************************************************************
   difftime.ml		Created      : Fri Sep 13 01:42:49 2002
  			Last modified: Fri Sep 13 03:05:08 2002
  Compile: ocamlopt.opt unix.cmxa difftime.ml -o difftime #
************************************************************)
(**
  時間の計算をしてみよう。
  @author Takashi Masuyama
  @see Unix.mktime
  @see Unix.tm
*)


let one_day = 24.0 *. 60.0 *. 60.0 (* sec *)
open Unix
(**
  年はtoupleで表す。
  @param (ty,tm,td) 終了日 (引くほう)
  @param (fy,fm,fd) 終了日 (引かれるほう)
*)
let difftime (ty,tm,td) (fy,fm,fd) =
  let from_tm = {
    tm_sec = 0; tm_min = 0; tm_hour = 0;
    tm_mday = fd; tm_mon = fm - 1; tm_year = fy - 1900;
    tm_wday = 0; tm_yday = 0; tm_isdst = false; 
  } in
  let to_tm = {
    tm_sec = 0; tm_min = 0; tm_hour = 0;
    tm_mday = td; tm_mon = tm - 1; tm_year = ty - 1900;
    tm_wday = 0; tm_yday = 0; tm_isdst = false; 
  } in
  let from_ft = fst (mktime from_tm) in
  let to_ft = fst (mktime to_tm) in
  int_of_float ((to_ft -. from_ft)/.one_day)

(* main 関数を書こう *)