Pattern Matching exercise

pattern_matching.erl

-module(pattern_matching).

-export([xOr_1/2,xOr_2/2,xOr_3/2,xOr_4/2,test_xOr_1/0,test_xOr_2/0,test_xOr_3/0,test_xOr_4/0,test_maxThree/0,test_howManyEqual/0]).


xOr_1(X,Y) -> 
	X =/= Y.

xOr_2(X,Y) -> 
       (X and not Y) or (not X and Y).	

xOr_3(X,Y) -> 
       (X or Y) and (not X or not Y).	

xOr_4(X,Y) -> 
	X xor Y.


maxThree(X,Y,Z) ->
	erlang:max(X,erlang:max(Y,Z)).


howManyEqual(X,X,X) -> 3;
howManyEqual(X,X,_) -> 2;
howManyEqual(X,_,X) -> 2;
howManyEqual(_,X,X) -> 2;
howManyEqual(_,_,_) -> 0.

%Tests functions begins here.
%Returns true if everything goes as expected.

test_xOr_1() ->
        (xOr_1(true,true) == false) and
        (xOr_1(true,false) == true).

test_xOr_2() ->
        (xOr_2(true,true) == false) and
        (xOr_2(true,false) == true).


test_xOr_3() ->
        (xOr_3(true,true) == false) and
        (xOr_3(true,false) == true).

test_xOr_4() ->
        (xOr_4(true,true) == false) and
        (xOr_4(true,false) == true).

test_maxThree() -> 
	maxThree(34,25,36) == 36.

test_howManyEqual() ->
	(howManyEqual(34,25,36) == 0) and
	(howManyEqual(34,25,34) == 2) and
	(howManyEqual(34,34,34) == 3).