funcprog: Ocaml assignments from week 2

funcprog/week2/ass5_1.ml

+let isLeapYear x =
+    x >= 1582 && x mod 4 == 0 && (x mod 100 != 0 || x mod 400 == 0)
+;;
+
+let testLeapYear x =
+    Printf.printf "%4d: %b\n" x (isLeapYear x);;
+
+(testLeapYear 1400);; (* false *)
+(testLeapYear 1582);; (* false *)
+(testLeapYear 1583);; (* false *)
+(testLeapYear 1584);; (* true *)
+(testLeapYear 1700);; (* false *)
+(testLeapYear 2000);; (* true *)

funcprog/week2/ass5_2.ml

+exception Hell
+
+let day_with_suffix day =
+    match day with
+      1 | 21 | 31     -> (string_of_int day) ^ "st"
+    | 2 | 22          -> (string_of_int day) ^ "nd"
+    | 3 | 23          -> (string_of_int day) ^ "rd"
+    | _ when day > 0  -> (string_of_int day) ^ "th"
+    | _               -> raise Hell
+;;
+
+let month_name month =
+    match month with
+      1  -> "January"
+    | 2  -> "February"
+    | 3  -> "March"
+    | 4  -> "April"
+    | 5  -> "May"
+    | 6  -> "June"
+    | 7  -> "July"
+    | 8  -> "August"
+    | 9  -> "September"
+    | 10 -> "October"
+    | 11 -> "November"
+    | 12 -> "December"
+    | _  -> raise Hell
+;;
+
+let date2str day month year =
+    Printf.sprintf "%s %s, %d" (month_name month) (day_with_suffix day) year
+;;
+
+(* correct date2str input: *)
+print_string (date2str 2 2 2011);;
+(* expected a raised Hell exception: *)
+print_string (date2str (-2) 2 2011);;

funcprog/week2/ass5_3.ml

+let rec digitRoot number =
+    let result = ref 0 in
+    let current = ref number in (
+        Printf.printf "input: %d\n" !current;
+
+        while !current > 0 do
+            result := !result + (!current mod 10);
+            Printf.printf "%d + " (!current mod 10);
+            current := !current / 10;
+        done;
+
+        Printf.printf "= %d\n" !result;
+
+        if !result > 9 then
+            (digitRoot !result)
+        else
+            !result
+    )
+;;
+
+let test_digitRoot input =
+    print_string "--- test_digitRoot ---\n";
+    Printf.printf "%d -> %d\n" input (digitRoot input)
+;;
+
+(test_digitRoot 20);;
+(test_digitRoot 24);;
+(test_digitRoot 1234);;
+(test_digitRoot 123456789);;
+(test_digitRoot (-1));; (* what to do with negative numbers? *)

funcprog/week2/ass5_4.ml

+let even_len x = 
+  if (x mod 2) == 0 then
+    x
+  else
+    x - 1
+  ;;
+
+let isPalindrome palin = 
+  let result = ref true in (
+  for i = 0 to ((even_len (String.length palin)) / 2) - 1 do
+    if (palin.[i] != palin.[(even_len (String.length palin)) - i - 1]) then
+      begin
+        result := false;
+      end
+    else
+      ()
+  done;
+  !result)
+  ;;
+
+Printf.printf "%b\n" (isPalindrome "asddsa") 
+