Add Refraction

num2words.go

@@ -27,6 +27,47 @@ var (
 	}
 )
 
+// ConvertDecimal converts decimal number into the words representation
+// reference: https://www.jawapos.com/opini/28/04/2019/membaca-desimal/
+func ConvertDecimal(number float64, precision int) (string, error) {
+	if precision < 1 {
+		return Convert(int64(number))
+	}
+
+	format := "%." + fmt.Sprintf("%d", precision) + "f"
+	fractions := fmt.Sprintf(format, number)
+	fractions = strings.Split(fractions, ".")[1]
+
+	words := ""
+	for precision > 0 {
+		v := fractions[precision-1] - 48
+		if v > 0 {
+			break
+		}
+		precision--
+	}
+
+	fractions = fractions[:precision]
+
+	for i := 1; i <= precision; i++ {
+		v := fractions[precision-i] - 48
+		words = smallNumbers[v] + " " + words
+	}
+
+	if words == "" {
+		return Convert(int64(number))
+	}
+
+	words = words[:len(words)-1]
+
+	numString, err := Convert(int64(number))
+	if err != nil {
+		return "", err
+	}
+
+	return numString + " koma " + words, nil
+}
+
 // Convert converts number into the words representation
 func Convert(number int64) (string, error) {
 
@@ -63,7 +104,7 @@ func Convert(number int64) (string, error) {
 func splitIntoThreeDigitGroups(number int64) []uint16 {
 	var digitGroups []uint16
 	for i := 0; i < len(scales); i++ {
-		digitGroups = append(digitGroups,uint16(number % 1000))
+		digitGroups = append(digitGroups, uint16(number%1000))
 		number = number / 1000
 	}
 	return digitGroups

num2words_test.go

@@ -109,7 +109,6 @@ func TestConvert(t *testing.T) {
 			assert.Equal(t, tt.Words, w)
 		})
 	}
-
 }
 
 func TestConvertMinus(t *testing.T) {
@@ -132,4 +131,44 @@ func TestConvertError(t *testing.T) {
 	w, err := Convert(1000000000000000)
 	assert.NotNil(t, err)
 	assert.Equal(t, "", w)
+
+	w, err = ConvertDecimal(1000000000000000.1, 1)
+	assert.NotNil(t, err)
+	assert.Equal(t, "", w)
+}
+
+var fractionTest = []struct {
+	Number    float64
+	Precision int
+	Words     string
+}{
+	{0.1, 1, "nol koma satu"},
+	{5.1, 1, "lima koma satu"},
+	{155.25, 1, "seratus lima puluh lima koma dua"},
+	{0.25, 2, "nol koma dua lima"},
+	{0.128, 3, "nol koma satu dua delapan"},
+	{0.128, 4, "nol koma satu dua delapan"},
+	{0.128, 0, "nol"},
+	{0.12345, 5, "nol koma satu dua tiga empat lima"},
+	{23.12345, 5, "dua puluh tiga koma satu dua tiga empat lima"},
+	{1.123456, 6, "satu koma satu dua tiga empat lima enam"},
+	{0.1234563, 6, "nol koma satu dua tiga empat lima enam"},
+	{0.1234563, 7, "nol koma satu dua tiga empat lima enam tiga"},
+	{0.12345639, 8, "nol koma satu dua tiga empat lima enam tiga sembilan"},
+	{0.02345639, 1, "nol"},
+	{0.02345639, 2, "nol koma nol dua"},
+	{0.00000, 5, "nol"},
+	{0.00001, 5, "nol koma nol nol nol nol satu"},
+	{0.10000, 5, "nol koma satu"},
+}
+
+func TestFraction(t *testing.T) {
+	t.Parallel()
+	for _, tt := range fractionTest {
+		t.Run("testconvert", func(t *testing.T) {
+			w, err := ConvertDecimal(tt.Number, tt.Precision)
+			assert.Nil(t, err)
+			assert.Equal(t, tt.Words, w)
+		})
+	}
 }