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
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;
}
}
其他回答
使用野田时间:
LocalDate start = new LocalDate(2013, 1, 5);
LocalDate end = new LocalDate(2014, 6, 1);
Period period = Period.Between(start, end, PeriodUnits.Months);
Console.WriteLine(period.Months); // 16
(例子)
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
}
扩展的Kirks结构与ToString(格式)和持续时间(长ms)
public struct DateTimeSpan
{
private readonly int years;
private readonly int months;
private readonly int days;
private readonly int hours;
private readonly int minutes;
private readonly int seconds;
private readonly int milliseconds;
public DateTimeSpan(int years, int months, int days, int hours, int minutes, int seconds, int milliseconds)
{
this.years = years;
this.months = months;
this.days = days;
this.hours = hours;
this.minutes = minutes;
this.seconds = seconds;
this.milliseconds = milliseconds;
}
public int Years { get { return years; } }
public int Months { get { return months; } }
public int Days { get { return days; } }
public int Hours { get { return hours; } }
public int Minutes { get { return minutes; } }
public int Seconds { get { return seconds; } }
public int Milliseconds { get { return milliseconds; } }
enum Phase { Years, Months, Days, Done }
public string ToString(string format)
{
format = format.Replace("YYYY", Years.ToString());
format = format.Replace("MM", Months.ToString());
format = format.Replace("DD", Days.ToString());
format = format.Replace("hh", Hours.ToString());
format = format.Replace("mm", Minutes.ToString());
format = format.Replace("ss", Seconds.ToString());
format = format.Replace("ms", Milliseconds.ToString());
return format;
}
public static DateTimeSpan Duration(long ms)
{
DateTime dt = new DateTime();
return CompareDates(dt, dt.AddMilliseconds(ms));
}
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();
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);
}
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;
}
}
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;
}
这是我所需要的。对我来说,一个月的哪一天并不重要,因为它总是碰巧是一个月的最后一天。
public static int MonthDiff(DateTime d1, DateTime d2){
int retVal = 0;
if (d1.Month<d2.Month)
{
retVal = (d1.Month + 12) - d2.Month;
retVal += ((d1.Year - 1) - d2.Year)*12;
}
else
{
retVal = d1.Month - d2.Month;
retVal += (d1.Year - d2.Year)*12;
}
//// Calculate the number of years represented and multiply by 12
//// Substract the month number from the total
//// Substract the difference of the second month and 12 from the total
//retVal = (d1.Year - d2.Year) * 12;
//retVal = retVal - d1.Month;
//retVal = retVal - (12 - d2.Month);
return retVal;
}