Data commit

Task/Number-names/Erlang/number-names.erl

@@ -0,0 +1,77 @@
+-module(nr2eng).
+-import(lists, [foreach/2, seq/2, append/2]).
+-import(string, [strip/3, str/2]).
+-export([start/0]).
+
+sym(1) -> "one";
+sym(2) -> "two";
+sym(3) -> "three";
+sym(4) -> "four";
+sym(5) -> "five";
+sym(6) -> "six";
+sym(7) -> "seven";
+sym(8) -> "eight";
+sym(9) -> "nine";
+sym(10) -> "ten";
+sym(11) -> "eleven";
+sym(12) -> "twelve";
+sym(13) -> "thirteen";
+sym(20) -> "twenty";
+sym(30) -> "thirty";
+sym(40) -> "forty";
+sym(50) -> "fifty";
+sym(100) -> "hundred";
+sym(1000) -> "thousand";
+sym(1000*1000) -> "million";
+sym(1000*1000*1000) -> "billion";
+sym(_) -> "".
+
+next(1000) -> 100;
+next(100) -> 10;
+next(10) -> 1;
+next(X) -> X div 1000.
+
+concat(PRE, "") ->
+   PRE;
+concat(PRE, POST) ->
+   PRE++" "++POST.
+concat("", _, POST) ->
+   POST;
+concat(PRE, SYM, "") ->
+   PRE++" "++SYM;
+concat(PRE, SYM, POST) ->
+   PRE++" "++SYM++" "++POST.
+
+nr2eng(0, _) ->
+   "";
+nr2eng(NR, 1) ->
+   sym(NR);
+nr2eng(NR, 10) when NR =< 20 ->
+   case sym(NR) of
+        "" -> strip(sym(NR-10), right, $t) ++ "teen";
+        _  -> sym(NR)
+   end;
+nr2eng(NR, 10) ->
+   concat(
+     case sym((NR div 10)*10) of
+        "" -> strip(sym(NR div 10), right, $t) ++ "ty";
+        _  -> sym((NR div 10)*10)
+     end,
+     nr2eng(NR rem 10, 1));
+nr2eng(NR, B) ->
+   PRE  = nr2eng(NR div B, next(B)),
+   POST = nr2eng(NR rem B, next(B)),
+   AND  = str(POST, "and"),
+   COMMA = if
+              POST == "" -> "";
+              AND == 0 -> " and";
+              B >= 1000 -> ",";
+              true -> ""
+   end,
+   concat(PRE,  sym(B)++COMMA, POST).
+
+start() ->
+   lists:foreach(
+     fun (X) -> io:fwrite("~p ~p ~n", [X, nr2eng(X, 1000000000)])
+     end,
+     append(seq(1, 2000), [123123, 43234234])).