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
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);
}
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;
}
这是我自己的库,将返回两个日期之间的月差。
public static int MonthDiff(DateTime d1, DateTime d2)
{
int retVal = 0;
// 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;
}
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
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
label3.Text = new DateDifference(Convert.ToDateTime("2018-09-13"), Convert.ToDateTime("2018-11-15")).ToString();
label2.Text = new DateDifference(Convert.ToDateTime("2018-10-12"), Convert.ToDateTime("2018-11-15")).ToString();
DateDifference oDateDifference = new DateDifference(Convert.ToDateTime("2018-11-12"));
label1.Text = oDateDifference.ToString();
}
}
public class DateDifference
{
public DateTime start { get; set; }
public DateTime currentDAte { get; set; }
public DateTime origstart { get; set; }
public DateTime origCurrentDAte { get; set; }
int days { get; set; }
int months { get; set; }
int years { get; set; }
public DateDifference(DateTime postedDate, DateTime currentDAte)
{
this.start = this.removeTime(postedDate);
this.currentDAte = this.removeTime(currentDAte);
this.origstart = postedDate;
this.origCurrentDAte = currentDAte;
}
public DateDifference(DateTime postedDate)
{
DateTime currentDate_ = DateTime.Now;
this.start = this.removeTime(postedDate);
this.currentDAte = this.removeTime(currentDate_);
this.origstart = postedDate;
this.origCurrentDAte = currentDate_;
if (start > this.currentDAte)
{
throw new Exception("Current date is greater than date posted");
}
this.compute();
}
void compute()
{
while (this.start.Year <= this.currentDAte.Year)
{
if (this.start.Year <= this.currentDAte.Year && (this.start.AddMonths(1) <= this.currentDAte))
{
++this.months;
this.start = this.start.AddMonths(1);
}
if ((this.start.Year == this.currentDAte.Year) && (this.start >= this.currentDAte.AddMonths(-1) && this.start <= this.currentDAte))
{
break;
}
}
while (this.start.DayOfYear < this.currentDAte.DayOfYear)
{
++this.days;
this.start = start.AddDays(1);
}
if (this.months > 11)
{
while (this.months > 11)
{
++this.years;
this.months = months - 12;
}
}
}
public override string ToString()
{
if (this.start > this.currentDAte)
{
throw new Exception("Current date is greater than date posted");
}
String ret = this.ComposeTostring();
this.reset();
return ret;
}
private String ComposeTostring()
{
this.compute();
if (this.years > 0)
{
if (this.months > 0)
{
if (this.days > 0)
{
return String.Format("{0} year{1}, {2} month{3} && {4} Day{5} ago", this.years, plural(this.years), this.months, plural(this.months), this.days, plural(this.days));
}
return String.Format("{0} year{1}, {2} month{3} ago", this.years, plural(this.years), this.months, plural(this.months));
}
else
{
if (this.days > 0)
{
return String.Format("{0} year{1},{2} day{3} ago", this.years, plural(this.years), this.days, plural(this.days));
}
return String.Format("{0} year{1} ago", this.years, plural(this.years));
}
}
if (this.months > 0)
{
if (this.days > 0)
{
return String.Format("{0} month{1}, {2} day{3} ago", this.months, plural(this.months), this.days, plural(this.days));
}
else
{
return String.Format("{0} month{1} ago", this.months, plural(this.months));
}
}
if ((this.origCurrentDAte - this.origstart).Days > 0)
{
int daysDiff = (this.origCurrentDAte - this.origstart).Days;
this.origstart = this.origstart.AddDays(daysDiff);
int HoursDiff = (this.origCurrentDAte - this.origstart).Hours;
return String.Format("{0} day{1}, {2} hour{3} ago", daysDiff, plural(daysDiff), HoursDiff, plural(HoursDiff));
}
else if ((this.origCurrentDAte - this.origstart).Hours > 0)
{
int HoursDiff = (this.origCurrentDAte - this.origstart).Hours;
this.origstart = this.origstart.AddHours(HoursDiff);
int MinDiff = (this.origCurrentDAte - this.origstart).Minutes;
return String.Format("{0} hour{1}, {2} minute{3} ago", HoursDiff, plural(HoursDiff), MinDiff, plural(MinDiff));
}
else if ((this.origCurrentDAte - this.origstart).Minutes > 0)
{
int MinDiff = (this.origCurrentDAte - this.origstart).Minutes;
this.origstart = this.origstart.AddMinutes(MinDiff);
int SecDiff = (this.origCurrentDAte - this.origstart).Seconds;
return String.Format("{0} minute{1}, {2} second{3} ago", MinDiff, plural(MinDiff), SecDiff, plural(SecDiff));
}
else if ((this.origCurrentDAte - this.origstart).Seconds > 0)
{
int sec = (this.origCurrentDAte - this.origstart).Seconds;
return String.Format("{0} second{1}", sec, plural(sec));
}
return "";
}
String plural(int val)
{
return (val > 1 ? "s" : String.Empty);
}
DateTime removeTime(DateTime dtime)
{
dtime = dtime.AddHours(-dtime.Hour);
dtime = dtime.AddMinutes(-dtime.Minute);
dtime = dtime.AddSeconds(-dtime.Second);
return dtime;
}
public void reset()
{
this.days = 0;
this.months = 0;
this.years = 0;
this.start = DateTime.MinValue;
this.currentDAte = DateTime.MinValue;
this.origstart = DateTime.MinValue;
this.origCurrentDAte = DateTime.MinValue;
}
}
以下是我对获得Months差异的贡献,我发现这是准确的:
namespace System
{
public static class DateTimeExtensions
{
public static Int32 DiffMonths( this DateTime start, DateTime end )
{
Int32 months = 0;
DateTime tmp = start;
while ( tmp < end )
{
months++;
tmp = tmp.AddMonths( 1 );
}
return months;
}
}
}
用法:
Int32 months = DateTime.Now.DiffMonths( DateTime.Now.AddYears( 5 ) );
您可以创建另一个名为DiffYears的方法,并应用与上面完全相同的逻辑,并在while循环中使用AddYears而不是AddMonths。