这里有一个非常简单且易于遵循的示例。

private int CalculateAge()
{
//get birthdate
   DateTime dtBirth = Convert.ToDateTime(BirthDatePicker.Value);
   int byear = dtBirth.Year;
   int bmonth = dtBirth.Month;
   int bday = dtBirth.Day;
   DateTime dtToday = DateTime.Now;
   int tYear = dtToday.Year;
   int tmonth = dtToday.Month;
   int tday = dtToday.Day;
   int age = tYear - byear;
   if (bmonth < tmonth)
       age--;
   else if (bmonth == tmonth && bday>tday)
   {
       age--;
   }
return age;
}

我创建了一个Age结构，如下所示：

public struct Age : IEquatable<Age>, IComparable<Age>
{
    private readonly int _years;
    private readonly int _months;
    private readonly int _days;

    public int Years  { get { return _years; } }
    public int Months { get { return _months; } }
    public int Days { get { return _days; } }

    public Age( int years, int months, int days ) : this()
    {
        _years = years;
        _months = months;
        _days = days;
    }

    public static Age CalculateAge( DateTime dateOfBirth, DateTime date )
    {
        // Here is some logic that ressembles Mike's solution, although it
        // also takes into account months & days.
        // Ommitted for brevity.
        return new Age (years, months, days);
    }

    // Ommited Equality, Comparable, GetHashCode, functionality for brevity.
}

试试这个解决方案，它奏效了。

int age = (Int32.Parse(DateTime.Today.ToString("yyyyMMdd")) - 
           Int32.Parse(birthday.ToString("yyyyMMdd rawrrr"))) / 10000;

我认为TimeSpan包含了我们所需要的一切，而不必求助于365.25（或任何其他近似值）。扩展Aug的示例：

DateTime myBD = new DateTime(1980, 10, 10);
TimeSpan difference = DateTime.Now.Subtract(myBD);

textBox1.Text = difference.Years + " years " + difference.Months + " Months " + difference.Days + " days";

MSDN帮助为什么没有告诉您这一点？看起来很明显：

System.DateTime birthTime = AskTheUser(myUser); // :-)
System.DateTime now = System.DateTime.Now;
System.TimeSpan age = now - birthTime; // As simple as that
double ageInDays = age.TotalDays; // Will you convert to whatever you want yourself?

通过较少的转换和UtcNow，这段代码可以照顾闰年2月29日出生的人：

public int GetAge(DateTime DateOfBirth)
{
    var Now = DateTime.UtcNow;
    return Now.Year - DateOfBirth.Year -
        (
            (
                Now.Month > DateOfBirth.Month ||
                (Now.Month == DateOfBirth.Month && Now.Day >= DateOfBirth.Day)
            ) ? 0 : 1
        );
}