Truth tables

To check the final result, to make sure that conditions and actions are correctly associated, we can use a truth table

Multiple alternative if

	if test_1 then
		statement(s)_1;
	elsif test_2 then
		statement(s)_2;
	elsif test_3 then
		statement(s)_3;
	else
		statement(s)_4;
	end if;

test_1	test_2	test_3	s_1	s_2	s_3	s_4
F	F	F				*
F	F	T			*
F	T	F		*
F	T	T		*
T	F	F	*
T	F	T	*
T	T	F	*
T	T	T	*

Nested if statements

	if test_1 then
		if test_2 then
			statement(s)_1;
		else
			statement(s)_2;
		end if;
	else
		if test_3 then
			statement(s)_3;
		else
			statement(s)_4;
		end if;
	end if;

test_1	test_2	test_3	s_1	s_2	s_3	s_4
F	F	F				*
F	F	T			*
F	T	F				*
F	T	T			*
T	F	F		*
T	F	T		*
T	T	F	*
T	T	T	*