从datetime字段计算年龄，包括时间跨度

我试图调用这个函数，它应该返回57的年龄，但如果我今天运行它，2016年10月18日返回58。

    DateTime myDate3test = Convert.ToDateTime("1958-10-17 13:45:59.473");
    Console.WriteLine(CalculateAge(myDate3test)); //this should return 57 if run today October 18, 2016 since the person is not yet 58

    public static string CalculateAge(DateTime dtDateOfBirth)
    {
        int age = 0;
        DateTime dtNow = DateTime.Now;
        string measurement = string.Empty;
        if (DateTime.Compare(dtNow, dtDateOfBirth) == 1)
        {
            TimeSpan tsAge = dtNow.Subtract(dtDateOfBirth);
            DateTime dtAge = new DateTime(tsAge.Ticks);

            var vNowDate = Convert.ToInt32(dtNow.ToString("yyyyMMdd"));
            var vBirthdate = Convert.ToInt32(dtDateOfBirth.ToString("yyyyMMdd"));
            double diff = (vNowDate - vBirthdate) / 10000;
            age = Convert.ToInt32(Math.Truncate(diff));
            measurement = " year";
            if (age == 0) // patient is not 1 year old yet
            {
                age = dtAge.Month - 1;
                measurement = " month";
                if (age == 0) // patient is not 1 month old yet
                {
                    age = dtAge.Day - 1;
                    measurement = " day";
                }
            }
            if (age > 1)
            {
                measurement += "s";
            }
        }
        else
        {
            // Future date!!!
            measurement = " Unable to calculate age";
            age = -1;
        }
        return age.ToString() + measurement;
    }