需求

验证信用卡号码是否有效 

func (I *Detector) verifyByCreditCard(res *dlpheader.DetectResult) bool {
	patternText := res.Text
	sanitizedValue := strings.Replace(patternText, "-", "", -1)
	numberLen := len(sanitizedValue)
	sum := 0
	alternate := false

	// length is not matched
	if numberLen < 13 || numberLen > 19 {
		return false
	}

	for i := numberLen - 1; i > -1; i-- {
		mod := int(byte(sanitizedValue[i]) - '0')
		if alternate {
			mod *= 2
			if mod > 9 {
				mod = (mod % 10) + 1
			}
		}
		alternate = !alternate
		sum += mod
	}
	return sum%10 == 0
}