Fix cif_id_for_number

src/text.cpp

@@ -236,28 +236,19 @@ std::string cif_id_for_number(int number)
 {
 	std::string result;
 
-	if (number >= 26 * 26 * 26)
-		result = 'L' + std::to_string(number);
-	else
-	{
-		if (number >= 26 * 26)
+	do
 	{
-			int v = number / (26 * 26);
-			result += char('A' - 1 + v);
-			number %= (26 * 26);
-		}
+		int r = number % 26;
+		result += 'A' + r;
 
-		if (number >= 26)
-		{
-			int v = number / 26;
-			result += char('A' - 1 + v);
-			number %= 26;
+		number = (number - r) / 26 - 1;
 	}
+	while (number >= 0);
 
-		result += char('A' + number);
-	}
+	std::reverse(result.begin(), result.end());
 
 	assert(not result.empty());
+
 	return result;
 }
 

test/unit-v2-test.cpp

@@ -75,6 +75,30 @@ bool init_unit_test()
 
 // --------------------------------------------------------------------
 
+BOOST_AUTO_TEST_CASE(id_1)
+{
+	BOOST_TEST(cif::cif_id_for_number(0) == "A");
+	BOOST_TEST(cif::cif_id_for_number(25) == "Z");
+	BOOST_TEST(cif::cif_id_for_number(26) == "AA");
+	BOOST_TEST(cif::cif_id_for_number(26 + 1) == "AB");
+
+	BOOST_TEST(cif::cif_id_for_number(26 + 26 * 26 - 1) == "ZZ");
+	BOOST_TEST(cif::cif_id_for_number(26 + 26 * 26) == "AAA");
+	BOOST_TEST(cif::cif_id_for_number(26 + 26 * 26 + 1) == "AAB");
+
+	std::set<std::string> testset;
+
+	for (int i = 0; i < 100000; ++i)
+	{
+		std::string id = cif::cif_id_for_number(i);
+		BOOST_TEST(testset.count(id) == 0);
+		testset.insert(id);
+	}
+	BOOST_TEST(testset.size() == 100000);
+}
+
+// --------------------------------------------------------------------
+
 BOOST_AUTO_TEST_CASE(cc_1)
 {
 	std::tuple<std::string_view, float, char> tests[] = {