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
疯狂的方法,计算所有的日子,超级精确
Helper类:
public class DaysInMonth
{
public int Days { get; set; }
public int Month { get; set; }
public int Year { get; set; }
public bool Full { get; set; }
}
功能:
public static List<DaysInMonth> MonthsDelta(DateTime start, DateTime end)
{
var dates = Enumerable.Range(0, 1 + end.Subtract(start).Days)
.Select(offset => start.AddDays(offset))
.ToArray();
DateTime? prev = null;
int days = 0;
List < DaysInMonth > list = new List<DaysInMonth>();
foreach (DateTime date in dates)
{
if (prev != null)
{
if(date.Month!=prev.GetValueOrDefault().Month)
{
DaysInMonth daysInMonth = new DaysInMonth();
daysInMonth.Days = days;
daysInMonth.Month = prev.GetValueOrDefault().Month;
daysInMonth.Year = prev.GetValueOrDefault().Year;
daysInMonth.Full = DateTime.DaysInMonth(daysInMonth.Year, daysInMonth.Month) == daysInMonth.Days;
list.Add(daysInMonth);
days = 0;
}
}
days++;
prev = date;
}
//------------------ add last
if (days > 0)
{
DaysInMonth daysInMonth = new DaysInMonth();
daysInMonth.Days = days;
daysInMonth.Month = prev.GetValueOrDefault().Month;
daysInMonth.Year = prev.GetValueOrDefault().Year;
daysInMonth.Full = DateTime.DaysInMonth(daysInMonth.Year, daysInMonth.Month) == daysInMonth.Days;
list.Add(daysInMonth);
}
return list;
}
其他回答
下面是一个返回DateTimeSpan的综合解决方案,它与TimeSpan类似,不同之处是它除了时间组件之外还包括所有的日期组件。
用法:
void Main()
{
DateTime compareTo = DateTime.Parse("8/13/2010 8:33:21 AM");
DateTime now = DateTime.Parse("2/9/2012 10:10:11 AM");
var dateSpan = DateTimeSpan.CompareDates(compareTo, now);
Console.WriteLine("Years: " + dateSpan.Years);
Console.WriteLine("Months: " + dateSpan.Months);
Console.WriteLine("Days: " + dateSpan.Days);
Console.WriteLine("Hours: " + dateSpan.Hours);
Console.WriteLine("Minutes: " + dateSpan.Minutes);
Console.WriteLine("Seconds: " + dateSpan.Seconds);
Console.WriteLine("Milliseconds: " + dateSpan.Milliseconds);
}
输出:
年:1 第五个月: 天:27 时间:1 分钟:36 50秒: 毫秒:0
为了方便起见,我将逻辑集中到DateTimeSpan结构体中,但是您可以将方法CompareDates移动到任何您认为合适的地方。还要注意,哪个日期在另一个日期之前并不重要。
public struct DateTimeSpan
{
public int Years { get; }
public int Months { get; }
public int Days { get; }
public int Hours { get; }
public int Minutes { get; }
public int Seconds { get; }
public int Milliseconds { get; }
public DateTimeSpan(int years, int months, int days, int hours, int minutes, int seconds, int milliseconds)
{
Years = years;
Months = months;
Days = days;
Hours = hours;
Minutes = minutes;
Seconds = seconds;
Milliseconds = milliseconds;
}
enum Phase { Years, Months, Days, Done }
public static DateTimeSpan CompareDates(DateTime date1, DateTime date2)
{
if (date2 < date1)
{
var sub = date1;
date1 = date2;
date2 = sub;
}
DateTime current = date1;
int years = 0;
int months = 0;
int days = 0;
Phase phase = Phase.Years;
DateTimeSpan span = new DateTimeSpan();
int officialDay = current.Day;
while (phase != Phase.Done)
{
switch (phase)
{
case Phase.Years:
if (current.AddYears(years + 1) > date2)
{
phase = Phase.Months;
current = current.AddYears(years);
}
else
{
years++;
}
break;
case Phase.Months:
if (current.AddMonths(months + 1) > date2)
{
phase = Phase.Days;
current = current.AddMonths(months);
if (current.Day < officialDay && officialDay <= DateTime.DaysInMonth(current.Year, current.Month))
current = current.AddDays(officialDay - current.Day);
}
else
{
months++;
}
break;
case Phase.Days:
if (current.AddDays(days + 1) > date2)
{
current = current.AddDays(days);
var timespan = date2 - current;
span = new DateTimeSpan(years, months, days, timespan.Hours, timespan.Minutes, timespan.Seconds, timespan.Milliseconds);
phase = Phase.Done;
}
else
{
days++;
}
break;
}
}
return span;
}
}
简单的修复。工作的100%
var exactmonth = (date1.Year - date2.Year) * 12 + date1.Month -
date2.Month + (date1.Day >= date2.Day ? 0 : -1);
Console.WriteLine(exactmonth);
简单快速的解决方案,计算2个日期之间的总月份。 如果你只想得到不同的月份,而不计算From date中的月份-只需从代码中删除+1。
public static int GetTotalMonths(DateTime From, DateTime Till)
{
int MonthDiff = 0;
for (int i = 0; i < 12; i++)
{
if (From.AddMonths(i).Month == Till.Month)
{
MonthDiff = i + 1;
break;
}
}
return MonthDiff;
}
在这个问题上没有很多明确的答案,因为你总是在假设事情。
这个解决方案在两个日期之间进行计算,假设您想保存一个月中的某一天进行比较,(这意味着在计算中考虑了这个月中的某一天)
例如,如果你的日期是2012年1月30日,2012年2月29日就不是一个月,但2013年3月1日就不是一个月。
它经过了相当彻底的测试,可能稍后我们会在使用时清理它,但这里:
private static int TotalMonthDifference(DateTime dtThis, DateTime dtOther)
{
int intReturn = 0;
bool sameMonth = false;
if (dtOther.Date < dtThis.Date) //used for an error catch in program, returns -1
intReturn--;
int dayOfMonth = dtThis.Day; //captures the month of day for when it adds a month and doesn't have that many days
int daysinMonth = 0; //used to caputre how many days are in the month
while (dtOther.Date > dtThis.Date) //while Other date is still under the other
{
dtThis = dtThis.AddMonths(1); //as we loop, we just keep adding a month for testing
daysinMonth = DateTime.DaysInMonth(dtThis.Year, dtThis.Month); //grabs the days in the current tested month
if (dtThis.Day != dayOfMonth) //Example 30 Jan 2013 will go to 28 Feb when a month is added, so when it goes to march it will be 28th and not 30th
{
if (daysinMonth < dayOfMonth) // uses day in month max if can't set back to day of month
dtThis.AddDays(daysinMonth - dtThis.Day);
else
dtThis.AddDays(dayOfMonth - dtThis.Day);
}
if (((dtOther.Year == dtThis.Year) && (dtOther.Month == dtThis.Month))) //If the loop puts it in the same month and year
{
if (dtOther.Day >= dayOfMonth) //check to see if it is the same day or later to add one to month
intReturn++;
sameMonth = true; //sets this to cancel out of the normal counting of month
}
if ((!sameMonth)&&(dtOther.Date > dtThis.Date))//so as long as it didn't reach the same month (or if i started in the same month, one month ahead, add a month)
intReturn++;
}
return intReturn; //return month
}
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;
}
}