如何在c#中计算两个日期之间的月差?
c#中是否有相当于VB的DateDiff()方法。我需要找出相隔数年的两个日期之间的月差。文档说我可以像这样使用TimeSpan:
TimeSpan ts = date1 - date2;
但这里的数据是以天为单位的。我不想把这个数字除以30,因为不是每个月都是30天,而且两个操作数的值相差很大,所以我担心除以30可能会得到错误的值。
有什么建议吗?
如何在c#中计算两个日期之间的月差?
c#中是否有相当于VB的DateDiff()方法。我需要找出相隔数年的两个日期之间的月差。文档说我可以像这样使用TimeSpan:
TimeSpan ts = date1 - date2;
但这里的数据是以天为单位的。我不想把这个数字除以30,因为不是每个月都是30天,而且两个操作数的值相差很大,所以我担心除以30可能会得到错误的值。
有什么建议吗?
当前回答
单线解决方案
首先,检查两个日期是否都在当前年份,如果不是,则获取全年的月份,然后从年初和年末添加月份。
DateTime dateFrom = new DateTime(2019, 2, 1);
DateTime dateTo = new DateTime(2021, 5, 25);
第一个月
var monthCount = dateFrom.Year != dateTo.Year ? ((dateTo.Year - dateFrom.Year - 1) * 12) + (13 - dateFrom.Month + dateTo.Month) : dateTo.Month - dateFrom.Month + 1;
结果= 28
没有第一个月
monthCount = dateFrom.Year != dateTo.Year ? ((dateTo.Year - dateFrom.Year - 1) * 12) + (12 - dateFrom.Month + dateTo.Month) : dateTo.Month - dateFrom.Month;
结果= 27
其他回答
最精确的方法是以月为单位的分数返回差值:
private double ReturnDiffereceBetweenTwoDatesInMonths(DateTime startDateTime, DateTime endDateTime)
{
double result = 0;
double days = 0;
DateTime currentDateTime = startDateTime;
while (endDateTime > currentDateTime.AddMonths(1))
{
result ++;
currentDateTime = currentDateTime.AddMonths(1);
}
if (endDateTime > currentDateTime)
{
days = endDateTime.Subtract(currentDateTime).TotalDays;
}
return result + days/endDateTime.GetMonthDays;
}
似乎DateTimeSpan解决方案使许多人满意。我不知道。让我们考虑一下:
BeginDate = 1972/2/29销售= 1972/4/28。
基于DateTimeSpan的答案是:
1年(s), 2个月(s)和0天(s)
我实现了一个方法,在此基础上,答案是:
1年、1个月及28天
显然没有两个月的时间。我想说的是,因为我们在开始日期的月末,剩下的实际上是整个3月加上结束日期(4月)的月份所经过的天数,所以1个月零28天。
如果你读到这里,你有兴趣,我把方法贴在下面。我在评论中解释了我所做的假设,因为有多少个月,月份的概念是一个不断变化的目标。多次测试,看看答案是否有意义。我通常选择相邻年份的考试日期,一旦我确认了答案,我就会前后移动一两天。到目前为止,它看起来不错,我相信你会发现一些bug:D。代码可能看起来有点粗糙,但我希望它足够清楚:
static void Main(string[] args) {
DateTime EndDate = new DateTime(1973, 4, 28);
DateTime BeginDate = new DateTime(1972, 2, 29);
int years, months, days;
GetYearsMonthsDays(EndDate, BeginDate, out years, out months, out days);
Console.WriteLine($"{years} year(s), {months} month(s) and {days} day(s)");
}
/// <summary>
/// Calculates how many years, months and days are between two dates.
/// </summary>
/// <remarks>
/// The fundamental idea here is that most of the time all of us agree
/// that a month has passed today since the same day of the previous month.
/// A particular case is when both days are the last days of their respective months
/// when again we can say one month has passed.
/// In the following cases the idea of a month is a moving target.
/// - When only the beginning date is the last day of the month then we're left just with
/// a number of days from the next month equal to the day of the month that end date represent
/// - When only the end date is the last day of its respective month we clearly have a
/// whole month plus a few days after the the day of the beginning date until the end of its
/// respective months
/// In all the other cases we'll check
/// - beginingDay > endDay -> less then a month just daysToEndofBeginingMonth + dayofTheEndMonth
/// - beginingDay < endDay -> full month + (endDay - beginingDay)
/// - beginingDay == endDay -> one full month 0 days
///
/// </remarks>
///
private static void GetYearsMonthsDays(DateTime EndDate, DateTime BeginDate, out int years, out int months, out int days ) {
var beginMonthDays = DateTime.DaysInMonth(BeginDate.Year, BeginDate.Month);
var endMonthDays = DateTime.DaysInMonth(EndDate.Year, EndDate.Month);
// get the full years
years = EndDate.Year - BeginDate.Year - 1;
// how many full months in the first year
var firstYearMonths = 12 - BeginDate.Month;
// how many full months in the last year
var endYearMonths = EndDate.Month - 1;
// full months
months = firstYearMonths + endYearMonths;
days = 0;
// Particular end of month cases
if(beginMonthDays == BeginDate.Day && endMonthDays == EndDate.Day) {
months++;
}
else if(beginMonthDays == BeginDate.Day) {
days += EndDate.Day;
}
else if(endMonthDays == EndDate.Day) {
days += beginMonthDays - BeginDate.Day;
}
// For all the other cases
else if(EndDate.Day > BeginDate.Day) {
months++;
days += EndDate.Day - BeginDate.Day;
}
else if(EndDate.Day < BeginDate.Day) {
days += beginMonthDays - BeginDate.Day;
days += EndDate.Day;
}
else {
months++;
}
if(months >= 12) {
years++;
months = months - 12;
}
}
你可以有一个这样的函数。
例如,从2012/12/27到2012/12/29变成3天。同样,从2012/12/15到2013/01/15变成了2个月,因为到2013/01/14是1个月。从15号开始是第二个月。
如果您不想在计算中包括这两天,则可以删除第二个if条件中的“=”。即从2012/12/15到2013/01/15为1个月。
public int GetMonths(DateTime startDate, DateTime endDate)
{
if (startDate > endDate)
{
throw new Exception("Start Date is greater than the End Date");
}
int months = ((endDate.Year * 12) + endDate.Month) - ((startDate.Year * 12) + startDate.Month);
if (endDate.Day >= startDate.Day)
{
months++;
}
return months;
}
这个简单的静态函数计算两个Datetimes之间的月份分数。
1.1. 到31.1。= 1.0 1.4. 到15.4。= 0.5 16.4. 到30.4。= 0.5 1.3. 到1.4。= 1 + 1/30
该函数假设第一个日期比第二个日期小。要处理负时间间隔,可以通过在开始时引入符号和变量交换来轻松地修改函数。
public static double GetDeltaMonths(DateTime t0, DateTime t1)
{
DateTime t = t0;
double months = 0;
while(t<=t1)
{
int daysInMonth = DateTime.DaysInMonth(t.Year, t.Month);
DateTime endOfMonth = new DateTime(t.Year, t.Month, daysInMonth);
int cutDay = endOfMonth <= t1 ? daysInMonth : t1.Day;
months += (cutDay - t.Day + 1) / (double) daysInMonth;
t = new DateTime(t.Year, t.Month, 1).AddMonths(1);
}
return Math.Round(months,2);
}
这里有一个简单的解决方案,至少对我来说是有效的。它可能不是最快的,因为它在循环中使用了很酷的DateTime的AddMonth功能:
public static int GetMonthsDiff(DateTime start, DateTime end)
{
if (start > end)
return GetMonthsDiff(end, start);
int months = 0;
do
{
start = start.AddMonths(1);
if (start > end)
return months;
months++;
}
while (true);
}