使用年份格式化TimeSpan
我有一个有两个日期属性的类： FirstDay和LastDay 。 LastDay为空。 我想生成一个字符串，格式为"x year(s) y day(s)" 。 如果总年数小于1，我想省略年份部分。 如果总天数小于1，我想省略天数部分。 如果几年或几天都是0，他们应该说“日/年”，而不是“日/年”。
例子：
2.2年：“2年73天”
1.002738年：“1年1天”
0.2年：“73天”
2年：“2年”
我有作品，但它很长：
private const decimal DaysInAYear = 365.242M;
public string LengthInYearsAndDays
{
get
{
var lastDay = this.LastDay ?? DateTime.Today;
var lengthValue = lastDay - this.FirstDay;
var builder = new StringBuilder();
var totalDays = (decimal)lengthValue.TotalDays;
var totalYears = totalDays / DaysInAYear;
var years = (int)Math.Floor(totalYears);
totalDays -= (years * DaysInAYear);
var days = (int)Math.Floor(totalDays);
Func<int, string> sIfPlural = value =>
value > 1 ? "s" : string.Empty;
if (years > 0)
{
builder.AppendFormat(
CultureInfo.InvariantCulture,
"{0} year{1}",
years,
sIfPlural(years));
if (days > 0)
{
builder.Append(" ");
}
}
if (days > 0)
{
builder.AppendFormat(
CultureInfo.InvariantCulture,
"{0} day{1}",
days,
sIfPlural(days));
}
var length = builder.ToString();
return length;
}
}
有没有更简洁的方式来做到这一点（但仍然可读）？
TimeSpan没有明确的“年”概念，因为它取决于开始和结束点。 （几个月是相似的 - 29天内有多少个月？呃，这取决于...）
为了给一个无耻的插头，我的Noda Time项目使这个非常简单：
using System;
using NodaTime;
public class Test
{
static void Main(string[] args)
{
LocalDate start = new LocalDate(2010, 6, 19);
LocalDate end = new LocalDate(2013, 4, 11);
Period period = Period.Between(start, end,
PeriodUnits.Years | PeriodUnits.Days);
Console.WriteLine("Between {0} and {1} are {2} years and {3} days",
start, end, period.Years, period.Days);
}
}
输出：
Between 19 June 2010 and 11 April 2013 are 2 years and 296 days
public string GetAgeText(DateTime birthDate)
{
const double ApproxDaysPerMonth = 30.4375;
const double ApproxDaysPerYear = 365.25;
/*
The above are the average days per month/year over a normal 4 year period
We use these approximations as they are more accurate for the next century or so
After that you may want to switch over to these 400 year approximations
ApproxDaysPerMonth = 30.436875
ApproxDaysPerYear = 365.2425
How to get theese numbers:
The are 365 days in a year, unless it is a leepyear.
Leepyear is every forth year if Year % 4 = 0
unless year % 100 == 1
unless if year % 400 == 0 then it is a leep year.
This gives us 97 leep years in 400 years.
So 400 * 365 + 97 = 146097 days.
146097 / 400 = 365.2425
146097 / 400 / 12 = 30,436875
Due to the nature of the leap year calculation, on this side of the year 2100
you can assume every 4th year is a leap year and use the other approximatiotions
*/
//Calculate the span in days
int iDays = (DateTime.Now - birthDate).Days;
//Calculate years as an integer division
int iYear = (int)(iDays / ApproxDaysPerYear);
//Decrease remaing days
iDays -= (int)(iYear * ApproxDaysPerYear);
//Calculate months as an integer division
int iMonths = (int)(iDays / ApproxDaysPerMonth);
//Decrease remaing days
iDays -= (int)(iMonths * ApproxDaysPerMonth);
//Return the result as an string
return string.Format("{0} years, {1} months, {2} days", iYear, iMonths, iDays);
}
我不会用TimeSpan来做这件事。 因为一个月中的天数和一年中的天数不再是恒定的，所以一旦超过几天，日期数学就会变得棘手。 这很可能就是为什么TimeSpan不包含Years和Months属性。 相反，我会确定两个DateTime值之间的年/月/日等数值，并相应地显示结果。