给定代表某人生日的DateTime,我如何计算他们的年龄(以年为单位)?
当前回答
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;
}
其他回答
我使用这个:
public static class DateTimeExtensions
{
public static int Age(this DateTime birthDate)
{
return Age(birthDate, DateTime.Now);
}
public static int Age(this DateTime birthDate, DateTime offsetDate)
{
int result=0;
result = offsetDate.Year - birthDate.Year;
if (offsetDate.DayOfYear < birthDate.DayOfYear)
{
result--;
}
return result;
}
}
另一个功能,不是我做的,而是在网上找到的,并做了一些改进:
public static int GetAge(DateTime birthDate)
{
DateTime n = DateTime.Now; // To avoid a race condition around midnight
int age = n.Year - birthDate.Year;
if (n.Month < birthDate.Month || (n.Month == birthDate.Month && n.Day < birthDate.Day))
age--;
return age;
}
我只想到了两件事:来自不使用公历的国家的人呢?DateTime。我认为现在是服务器特定的文化。我对实际使用亚洲日历一无所知,我不知道是否有一种简单的方法来转换日历之间的日期,但以防万一,你想知道4660年的中国人:-)
==常见说法(从几个月到几岁)===
如果您只是为了通用,以下是代码作为您的信息:
DateTime today = DateTime.Today;
DateTime bday = DateTime.Parse("2016-2-14");
int age = today.Year - bday.Year;
var unit = "";
if (bday > today.AddYears(-age))
{
age--;
}
if (age == 0) // Under one year old
{
age = today.Month - bday.Month;
age = age <= 0 ? (12 + age) : age; // The next year before birthday
age = today.Day - bday.Day >= 0 ? age : --age; // Before the birthday.day
unit = "month";
}
else {
unit = "year";
}
if (age > 1)
{
unit = unit + "s";
}
测试结果如下:
The birthday: 2016-2-14
2016-2-15 => age=0, unit=month;
2016-5-13 => age=2, unit=months;
2016-5-14 => age=3, unit=months;
2016-6-13 => age=3, unit=months;
2016-6-15 => age=4, unit=months;
2017-1-13 => age=10, unit=months;
2017-1-14 => age=11, unit=months;
2017-2-13 => age=11, unit=months;
2017-2-14 => age=1, unit=year;
2017-2-15 => age=1, unit=year;
2017-3-13 => age=1, unit=year;
2018-1-13 => age=1, unit=year;
2018-1-14 => age=1, unit=year;
2018-2-13 => age=1, unit=year;
2018-2-14 => age=2, unit=years;
private int GetYearDiff(DateTime start, DateTime end)
{
int diff = end.Year - start.Year;
if (end.DayOfYear < start.DayOfYear) { diff -= 1; }
return diff;
}
[Fact]
public void GetYearDiff_WhenCalls_ShouldReturnCorrectYearDiff()
{
//arrange
var now = DateTime.Now;
//act
//assert
Assert.Equal(24, GetYearDiff(new DateTime(1992, 7, 9), now)); // passed
Assert.Equal(24, GetYearDiff(new DateTime(1992, now.Month, now.Day), now)); // passed
Assert.Equal(23, GetYearDiff(new DateTime(1992, 12, 9), now)); // passed
}
人们可以这样计算“年龄”(即“西方人”的方式):
public static int AgeInYears(this System.DateTime source, System.DateTime target)
=> target.Year - source.Year is int age && age > 0 && source.AddYears(age) > target ? age - 1 : age < 0 && source.AddYears(age) < target ? age + 1 : age;
如果时间方向为“负”,则年龄也将为负。
可以添加一个分数,代表从目标到下一个生日的累计年龄:
public static double AgeInTotalYears(this System.DateTime source, System.DateTime target)
{
var sign = (source <= target ? 1 : -1);
var ageInYears = AgeInYears(source, target); // The method above.
var last = source.AddYears(ageInYears);
var next = source.AddYears(ageInYears + sign);
var fractionalAge = (double)(target - last).Ticks / (double)(next - last).Ticks * sign;
return ageInYears + fractionalAge;
}
分数是过去的时间(从上一个生日到下一个生日)与总时间的比率。
无论是向前还是向后,这两种方法都以相同的方式工作。
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