c# 根据当前日期获取开始日期和最后日期

Question

我正在做一个基于日期的活动监视器，类似于stackoverflow Today,YesterDay,this week,Last week,this month,last Month.....基于当前日期如何在c#中为所有这些Today,YesterDay,this week,Last week,this month,last Month获取start-date和end-date？

Answer 1

DateTime baseDate = DateTime.Today;

var today = baseDate;
var yesterday = baseDate.AddDays(-1);
var thisWeekStart = baseDate.AddDays(-(int)baseDate.DayOfWeek);
var thisWeekEnd = thisWeekStart.AddDays(7).AddSeconds(-1);
var lastWeekStart = thisWeekStart.AddDays(-7);
var lastWeekEnd = thisWeekStart.AddSeconds(-1);
var thisMonthStart = baseDate.AddDays(1 - baseDate.Day);
var thisMonthEnd = thisMonthStart.AddMonths(1).AddSeconds(-1);
var lastMonthStart = thisMonthStart.AddMonths(-1);
var lastMonthEnd = thisMonthStart.AddSeconds(-1);

Answer 2

public enum FrequencyType
{
None = 0,
Daily = 1,
Weekly = 2,
Monthly = 3,
Quarterly = 4,
Annually = 5,
}


private string[] GetRange(FrequencyType frequency, DateTime dateToCheck)
{
string[] result = new string [2];
DateTime dateRangeBegin = dateToCheck;
TimeSpan duration = new TimeSpan(0, 0, 0, 0); //One day 
DateTime dateRangeEnd = DateTime.Today.Add(duration);

switch (frequency)
{
    case FrequencyType.Daily:
        dateRangeBegin = dateToCheck;
        dateRangeEnd = dateRangeBegin;
        break;

    case FrequencyType.Weekly:
        dateRangeBegin = dateToCheck.AddDays(-(int)dateToCheck.DayOfWeek);
        dateRangeEnd = dateToCheck.AddDays(6 - (int)dateToCheck.DayOfWeek);
        break;

    case FrequencyType.Monthly:
        duration = new TimeSpan(DateTime.DaysInMonth ( dateToCheck.Year, dateToCheck.Month) - 1 , 0, 0, 0);
        dateRangeBegin = dateToCheck.AddDays((-1) * dateToCheck.Day + 1);
        dateRangeEnd = dateRangeBegin.Add(duration); 
        break;

    case FrequencyType.Quarterly:
        int currentQuater = (dateToCheck.Date.Month - 1) / 3 + 1;
        int daysInLastMonthOfQuarter = DateTime.DaysInMonth(dateToCheck.Year, 3 * currentQuater );
        dateRangeBegin = new DateTime ( dateToCheck.Year, 3 * currentQuater - 2, 1);
        dateRangeEnd = new DateTime(dateToCheck.Year, 3 * currentQuater ,  daysInLastMonthOfQuarter);
        break;

    case FrequencyType.Annually:
       dateRangeBegin = new DateTime(dateToCheck.Year, 1, 1);
       dateRangeEnd = new DateTime(dateToCheck.Year, 12, 31); 
       break;
}
result[0] = dateRangeBegin.Date.ToString();
result[1] = dateRangeEnd.Date.ToString();
return result; 
}

http://zamirsblog.blogspot.com/2010/02/find-first-and-last-date-of-given-week.html

Answer 3

我希望这会有所帮助：

var begindate = new DateTime(DateTime.Now.Year, DateTime.Now.Month, 1).ToString("MM/dd/yyyy");
Console.WriteLine("FIRST DAY OF THE CURRENT MONTH (begindate): " + begindate);

var enddate=DateTime.Now.ToString("MM/dd/yyyy");
Console.WriteLine("TODAY'S DATE (enddate): " + enddate);

var comparebegindate = new DateTime(DateTime.Now.Year, DateTime.Now.Month-1, 1).ToString("MM/dd/yyyy");
Console.WriteLine("FIRST DAY OF THE LAST MONTH (comparebegindate): " + comparebegindate);

var comparedate = new DateTime(DateTime.Now.Year, DateTime.Now.Month - 1, DateTime.Now.Day).ToString("MM/dd/yyyy");
Console.WriteLine("TODAY'S DATE WITH LAST MONTH (comparedate): " + comparedate);

var compareenddate = new DateTime(DateTime.Now.Year, DateTime.Now.Month - 1, DateTime.DaysInMonth(DateTime.Now.Year, DateTime.Now.Month)).ToString("MM/dd/yyyy");
Console.WriteLine("LAST MONTH'S LAST DATE (compareenddate): " + compareenddate);