Source code in the basic256 programming language

call four_square(1, 7,  TRUE,  TRUE)
call four_square(3, 9,  TRUE,  TRUE)
call four_square(0, 9, FALSE, FALSE)
end

subroutine four_square(low, high, unique, show)
	total = 0

	if show then print " a b c d e f g" + chr(10) + " ============="

	for a = low to high
		for b = low to high
			if unique and b = a then continue for
			t = a + b
			for c = low to high
				if unique then
					if c = a or c = b then continue for
				end if
				for d = low to high
					if unique then
						if d = a or d = b or d = c then continue for
					end if
					if b + c + d = t then
						for e = low to high
							if unique then
								if e = a or e = b or e = c or e = d then continue for
							end if
							for f = low to high
								if unique then
									if f = a or f = b or f = c or f = d or f = e then continue for
								end if
								if d + e + f = t then
									for g = low to high
										if unique then
											if g = a or g = b or g = c or g = d or g = e or g = f then continue for
										end if
										if f + g = t then
											total += 1
											if show then print " ";a;" ";b;" ";c;" ";d;" ";e;" ";f;" ";g
										end if
									next g
								end if
							next f
						next e
					end if
				next d
			next c
		next b
	next a

	print
	if unique then
		print "There are ";total;" unique solutions in [";string(low);", ";string(high);"]"
	else
		print "There are ";total;" non-unique solutions in [";string(low);", ";string(high);"]"
	end if
	print
end subroutine