C# consiguen fecha de inicio y la última fecha de base a la fecha actual

Question

que estoy haciendo un monitor de actividad basado en la fecha que es similar a stackoverflow Today,YesterDay,this week,Last week,this month,last Month ..... basado en fecha actual como llegar start-date y end-date porque todas estas Today,YesterDay,this week,Last week,this month,last Month Cª#?

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

espero que esto ayudará a:

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);