How can I get the start and end date of a given year (int),开发者_高级运维 given month (int), and given week (int) { example Year : 2011 Month: 07 week: 04 } in c# 4.0? Thanks in advance.
The Start Date of the Year 2011 Month 07 and the week number of the month is 04.
Google is your friend.
Months:
public DateTime FirstDayOfMonthFromDateTime(DateTime dateTime)
{
return new DateTime(dateTime.Year, dateTime.Month, 1);
}
public DateTime LastDayOfMonthFromDateTime(DateTime dateTime)
{
DateTime firstDayOfTheMonth = new DateTime(dateTime.Year, dateTime.Month, 1);
return firstDayOfTheMonth.AddMonths(1).AddDays(-1);
}
You can do something similar for years:
DateTime time = new DateTime(2011,1,1);
time.AddYears(1).AddDays(-1);
And week needs to use the CultureInfo.FirstDay (or whatever you want to set as the first day of a week, in some countries it's Monday, sometimes it's Sunday).
/// <summary>
/// Returns the first day of the week that the specified
/// date is in using the current culture.
/// </summary>
public static DateTime GetFirstDayOfWeek(DateTime dayInWeek)
{
CultureInfo defaultCultureInfo = CultureInfo.CurrentCulture;
return GetFirstDateOfWeek(dayInWeek, defaultCultureInfo);
}
/// <summary>
/// Returns the first day of the week that the specified date
/// is in.
/// </summary>
public static DateTime GetFirstDayOfWeek(DateTime dayInWeek, CultureInfo cultureInfo)
{
DayOfWeek firstDay = cultureInfo.DateTimeFormat.FirstDayOfWeek;
DateTime firstDayInWeek = dayInWeek.Date;
while (firstDayInWeek.DayOfWeek != firstDay)
firstDayInWeek = firstDayInWeek.AddDays(-1);
return firstDayInWeek;
}
Not sure, but is this what you're after?
var weekStart = new DateTime(year, month, 1).AddDays(week * 7);
var weekEnd = weekStart.AddDays(6);
Assuming you start with week 1:
var startDate = new DateTime(year, month, 1).AddDays((week - 1) * 7);
var endDate = startDate.AddDays(6);
You could also use
DateTime.DaysInMonth(int year,int month);
to figure it out. The weeks will be more difficult.
DateTime calculations as these are a bit tricky, with some assumptions i could come up with this
//assign it to the first day of the month
DateTime getweek = new DateTime(2011, 4, 1);
// say the week starts on a Sunday
while (getweek.DayOfWeek != DayOfWeek.Sunday)
getweek = getweek.AddDays(1);
DateTimeFormatInfo info = DateTimeFormatInfo.CurrentInfo;
Calendar cal = info.Calendar;
//Now you are on the first week add 3 more to move to the Fourth week
DateTime start = cal.AddWeeks(getweek, 3); // 24 April 2011
DateTime end = start.AddDays(6); // 30 April 2011
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