这将显示下个月的最后日期。可以从AddMonths(x)中添加或减去想要返回的月份。

DateTime.Now.AddMonths(2).AddDays(-DateTime.Now.Day)

从下个月的第一天减去一天:

DateTime lastDay = new DateTime(MyDate.Year,MyDate.Month+1,1).AddDays(-1);

此外，如果你也需要它在12月工作:

DateTime lastDay = new DateTime(MyDate.Year,MyDate.Month,1).AddMonths(1).AddDays(-1);

你可以通过一行代码找到这个月的最后一天:

int maxdt = (new DateTime(dtfrom.Year, dtfrom.Month, 1).AddMonths(1).AddDays(-1)).Day;

另一种获取结束日期的方法:

    private static DateTime GetMonthEndDate(DateTime date)
    {
        DateTime endDate = date;
        int endDateMonth = endDate.Month;

        while (endDateMonth == endDate.Month)
            endDate = endDate.AddDays(1);

        endDate = endDate.AddDays(-1);

        return endDate;
    }

var lastDayOfMonth = DateTime.DaysInMonth(date.Year, date.Month);

// Use any date you want, for the purpose of this example we use 1980-08-03.
var myDate = new DateTime(1980,8,3);
var lastDayOfMonth = new DateTime(myDate.Year, myDate.Month, DateTime.DaysInMonth(myDate.Year, myDate.Month));