这很简单，似乎符合我的需要。我为闰年的目的做了一个假设，即无论一个人选择什么时候庆祝生日，从技术上讲，他们都不会比自己大一岁，直到他们的上一个生日过去365天（即2月28日不会使他们大一岁）。

DateTime now = DateTime.Today;
DateTime birthday = new DateTime(1991, 02, 03);//3rd feb

int age = now.Year - birthday.Year;

if (now.Month < birthday.Month || (now.Month == birthday.Month && now.Day < birthday.Day))//not had bday this year yet
  age--;

return age;

简单易懂的解决方案。

// Save today's date.
var today = DateTime.Today;

// Calculate the age.
var age = today.Year - birthdate.Year;

// Go back to the year in which the person was born in case of a leap year
if (birthdate.Date > today.AddYears(-age)) age--;

然而，这假设你在寻找西方的时代观念，而不是使用东亚的推算法。

private int GetAge(int _year, int _month, int _day
{
    DateTime yourBirthDate= new DateTime(_year, _month, _day);

    DateTime todaysDateTime = DateTime.Today;
    int noOfYears = todaysDateTime.Year - yourBirthDate.Year;

    if (DateTime.Now.Month < yourBirthDate.Month ||
        (DateTime.Now.Month == yourBirthDate.Month && DateTime.Now.Day < yourBirthDate.Day))
    {
        noOfYears--;
    }

    return  noOfYears;
}

这是一个非常简单的方法：

int Age = DateTime.Today.Year - new DateTime(2000, 1, 1).Year;

只需使用：

(DateTime.Now - myDate).TotalHours / 8766.0

当前日期-myDate=TimeSpan，获取总小时数并除以每年的总小时数，得到确切的年龄/月/日。。。

只是因为我认为最重要的答案不是那么明确：

public static int GetAgeByLoop(DateTime birthday)
{
    var age = -1;

    for (var date = birthday; date < DateTime.Today; date = date.AddYears(1))
    {
        age++;
    }

    return age;
}