Given a year, report if it is a leap year.
The tricky thing here is that a leap year in the Gregorian calendar occurs:
on every year that is evenly divisible by 4 except every year that is evenly divisible by 100 unless the year is also evenly divisible by 400
For example, 1997 is not a leap year, but 1996 is. 1900 is not a leap year, but 2000 is.
If your language provides a method in the standard library that does this look-up, pretend it doesn't exist and implement it yourself.
Though our exercise adopts some very simple rules, there is more to learn!
For a delightful, four minute explanation of the whole leap year phenomenon, go watch this youtube video.
For installation and learning resources, refer to the exercism help page.
To work on the exercises, you will need
Base. Consult opam website for instructions on how to install
opam for your OS. Once
opam is installed open a terminal window and run the following command to install base:
opam install base
To run the tests you will need
OUnit. Install it using
opam install ounit
A Makefile is provided with a default target to compile your solution and run the tests. At the command line, type:
utop is a command line program which allows you to run Ocaml code interactively. The easiest way to install it is via opam:
opam install utop
Consult utop for more detail.
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JavaRanch Cattle Drive, exercise 3 http://www.javaranch.com/leap.jsp
It's possible to submit an incomplete solution so you can see how others have completed the exercise.
open OUnit2 open Leap let ae exp got _test_ctxt = assert_equal exp got ~printer:string_of_bool let tests = [ "year not divisible by 4: common year" >:: ae false (leap_year 2015); "year divisible by 4, not divisible by 100: leap year" >:: ae true (leap_year 1996); "year divisible by 100, not divisible by 400: common year" >:: ae false (leap_year 2100); "year divisible by 400: leap year" >:: ae true (leap_year 2000); "year divisible by 200, not divisible by 400: common year" >:: ae false (leap_year 1800); ] let () = run_test_tt_main ("leap tests" >::: tests)
let leap_year y = y mod 4 = 0 && (y mod 100 <> 0 || y mod 400 = 0)
A huge amount can be learned from reading other people’s code. This is why we wanted to give exercism users the option of making their solutions public.
Here are some questions to help you reflect on this solution and learn the most from it.