我在这个问题上使用了以下内容。我知道它不太优雅，但它很管用。

DateTime zeroTime = new DateTime(1, 1, 1);
var date1 = new DateTime(1983, 03, 04);
var date2 = DateTime.Now;
var dif = date2 - date1;
int years = (zeroTime + dif).Year - 1;
Log.DebugFormat("Years -->{0}", years);

这是最准确的答案之一，它能够解决2月29日的生日，而不是2月28日的任何一年。

public int GetAge(DateTime birthDate)
{
    int age = DateTime.Now.Year - birthDate.Year;

    if (birthDate.DayOfYear > DateTime.Now.DayOfYear)
        age--;

    return age;
}

这是一个非常简单的方法：

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

我已经创建了一个SQL Server用户定义函数来计算某人的年龄，给定他们的出生日期。当您需要它作为查询的一部分时，这很有用：

using System;
using System.Data;
using System.Data.Sql;
using System.Data.SqlClient;
using System.Data.SqlTypes;
using Microsoft.SqlServer.Server;

public partial class UserDefinedFunctions
{
    [SqlFunction(DataAccess = DataAccessKind.Read)]
    public static SqlInt32 CalculateAge(string strBirthDate)
    {
        DateTime dtBirthDate = new DateTime();
        dtBirthDate = Convert.ToDateTime(strBirthDate);
        DateTime dtToday = DateTime.Now;

        // get the difference in years
        int years = dtToday.Year - dtBirthDate.Year;

        // subtract another year if we're before the
        // birth day in the current year
        if (dtToday.Month < dtBirthDate.Month || (dtToday.Month == dtBirthDate.Month && dtToday.Day < dtBirthDate.Day))
            years=years-1;

        int intCustomerAge = years;
        return intCustomerAge;
    }
};

2需要解决的主要问题有：

1.计算准确年龄-以年、月、日等为单位。

2.计算人们普遍认为的年龄——人们通常不关心自己到底多大，他们只关心自己当年的生日是什么时候。

1的解决方案显而易见：

DateTime birth = DateTime.Parse("1.1.2000");
DateTime today = DateTime.Today;     //we usually don't care about birth time
TimeSpan age = today - birth;        //.NET FCL should guarantee this as precise
double ageInDays = age.TotalDays;    //total number of days ... also precise
double daysInYear = 365.2425;        //statistical value for 400 years
double ageInYears = ageInDays / daysInYear;  //can be shifted ... not so precise

2的解决方案在确定总年龄时并不那么精确，但人们认为它是精确的。当人们“手动”计算年龄时，通常也会使用它：

DateTime birth = DateTime.Parse("1.1.2000");
DateTime today = DateTime.Today;
int age = today.Year - birth.Year;    //people perceive their age in years

if (today.Month < birth.Month ||
   ((today.Month == birth.Month) && (today.Day < birth.Day)))
{
  age--;  //birthday in current year not yet reached, we are 1 year younger ;)
          //+ no birthday for 29.2. guys ... sorry, just wrong date for birth
}

注释2.：

这是我的首选解决方案我们不能使用DateTime.DayOfYear或TimeSpans，因为它们会在闰年中改变天数为了可读性，我只增加了几行

还有一个提示。。。我将为它创建两个静态重载方法，一个用于通用，另一个用于使用友好：

public static int GetAge(DateTime bithDay, DateTime today) 
{ 
  //chosen solution method body
}

public static int GetAge(DateTime birthDay) 
{ 
  return GetAge(birthDay, DateTime.Now);
}

我认为这个问题可以用这样一种更简单的方法解决-

该类可以是-

using System;

namespace TSA
{
    class BirthDay
    {
        double ageDay;
        public BirthDay(int day, int month, int year)
        {
            DateTime birthDate = new DateTime(year, month, day);
            ageDay = (birthDate - DateTime.Now).TotalDays; //DateTime.UtcNow
        }

        internal int GetAgeYear()
        {
            return (int)Math.Truncate(ageDay / 365);
        }

        internal int GetAgeMonth()
        {
            return (int)Math.Truncate((ageDay % 365) / 30);
        }
    }
}

电话可以是这样的-

BirthDay b = new BirthDay(1,12,1990);
int year = b.GetAgeYear();
int month = b.GetAgeMonth();