Function NewFromString

decimal.go:180–249

NewFromString returns a new Decimal from a string representation. Trailing zeroes are not trimmed. Example: d, err := NewFromString("-123.45") d2, err := NewFromString(".0001") d3, err := NewFromString("1.47000")

(value string)

//	d2, err := NewFromString(".0001")
//	d3, err := NewFromString("1.47000")
func NewFromString(value string) (Decimal, error) {
	originalInput := value
	var intString string
	var exp int64

	// Check if number is using scientific notation
	eIndex := strings.IndexAny(value, "Ee")
	if eIndex != -1 {
		expInt, err := strconv.ParseInt(value[eIndex+1:], 10, 32)
		if err != nil {
			if e, ok := err.(*strconv.NumError); ok && e.Err == strconv.ErrRange {
				return Decimal{}, fmt.Errorf("can't convert %s to decimal: fractional part too long", value)
			}
			return Decimal{}, fmt.Errorf("can't convert %s to decimal: exponent is not numeric", value)
		}
		value = value[:eIndex]
		exp = expInt
	}

	pIndex := -1
	vLen := len(value)
	for i := 0; i < vLen; i++ {
		if value[i] == '.' {
			if pIndex > -1 {
				return Decimal{}, fmt.Errorf("can't convert %s to decimal: too many .s", value)
			}
			pIndex = i
		}
	}

	if pIndex == -1 {
		// There is no decimal point, we can just parse the original string as
		// an int
		intString = value
	} else {
		if pIndex+1 < vLen {
			intString = value[:pIndex] + value[pIndex+1:]
		} else {
			intString = value[:pIndex]
		}
		expInt := -len(value[pIndex+1:])
		exp += int64(expInt)
	}

	var dValue *big.Int
	// strconv.ParseInt is faster than new(big.Int).SetString so this is just a shortcut for strings we know won't overflow
	if len(intString) <= 18 {
		parsed64, err := strconv.ParseInt(intString, 10, 64)
		if err != nil {
			return Decimal{}, fmt.Errorf("can't convert %s to decimal", value)
		}
		dValue = big.NewInt(parsed64)
	} else {
		dValue = new(big.Int)
		_, ok := dValue.SetString(intString, 10)
		if !ok {
			return Decimal{}, fmt.Errorf("can't convert %s to decimal", value)
		}