DxCk的评论是有效的。即使一年的第一周或最后一周跨越两个不同的年份，此解决方案也能正常工作：
检查两个日期的第一天是否落在同一天。
以下是代码：
private bool DatesAreInTheSameWeek(DateTime date1, DateTime date2)
{
var cal = System.Globalization.DateTimeFormatInfo.CurrentInfo.Calendar;
var d1 = date1.Date.AddDays(-1 * (int)cal.GetDayOfWeek(date1));
var d2 = date2.Date.AddDays(-1 * (int)cal.GetDayOfWeek(date2));
return d1 == d2;
}
1来轻松解决这个问题：date1.AddDays(-((int)date1.DayOfWeek-1))。在我看来，这应该是被接受的答案。 - Simon Hänisch为什么不呢？
bool AreFallingInSameWeek(DateTime date1, DateTime date2)
{
return date1.AddDays(-(int)date1.DayOfWeek) == date2.AddDays(-(int)date2.DayOfWeek);
}
如果你想使用周的起始日为除了星期天以外的其他日子
bool AreFallingInSameWeek(DateTime date1, DateTime date2, DayOfWeek weekStartsOn)
{
return date1.AddDays(-GetOffsetedDayofWeek(date1.DayOfWeek, (int)weekStartsOn)) == date2.AddDays(-GetOffsetedDayofWeek(date2.DayOfWeek, (int)weekStartsOn));
}
int GetOffsetedDayofWeek(DayOfWeek dayOfWeek, int offsetBy)
{
return (((int)dayOfWeek - offsetBy + 7) % 7)
}
.Date 即可仅比较日期，代码如下：
return date1.AddDays(-(int)date1.DayOfWeek).Date == date2.AddDays(-(int)date2.DayOfWeek).Date; - david-so检查DateTime.Year和Calendar.GetWeekOfYear(DateTime, ...)。不需要检查月份。
编辑：这是错误的，但我无法删除它。请参见下面@Sparrow的答案。
使用 Calendar 类的 public virtual int GetWeekOfYear(DateTime time, CalendarWeekRule rule, DayOfWeek firstDayOfWeek) 方法
我的要求是找到本周出生日期。希望这可以解决你的疑惑。基本上，这段代码背后的思想如下：
check if the current year birthday falls between first day and last day of today's week.
private bool DatesAreInTheSameWeek(DateTime birthday)
{
if (birthday == DateTime.MinValue)
{
return false;
}
else
{
var birtdayWithCurrentYear = new DateTime(DateTime.Today.Year, birthday.Month, birthday.Day);
if (birthday.Month == 1 && DateTime.Today.Month != 1)
{
birtdayWithCurrentYear = birtdayWithCurrentYear.AddYears(1);
}
DateTime firstDayInWeek = DateTime.Today.Date;
while (firstDayInWeek.DayOfWeek != CultureInfo.CurrentCulture.DateTimeFormat.FirstDayOfWeek)
firstDayInWeek = firstDayInWeek.AddDays(-1);var lastDayInWeek = firstDayInWeek.AddDays(7);
return birtdayWithCurrentYear < lastDayInWeek && birtdayWithCurrentYear >= firstDayInWeek;
}
}
public static bool DateInsideOneWeek(DateTime date1, DateTime date2)
{
DayOfWeek firstDayOfWeek = System.Globalization.CultureInfo.CurrentCulture.DateTimeFormat.FirstDayOfWeek;
DateTime startDateOfWeek = date1.Date;
while(startDateOfWeek.DayOfWeek != firstWeekDay)
{ startDateOfWeek = startDateOfWeek.AddDays(-1d); }
DateTime endDateOfWeek = startDateOfWeek.AddDays(6d);
return date2 >= startDateOfWeek && date2 <= endDateOfWeek;
}
由于被接受的答案中存在错误，正如@DxCK在评论中提到的那样，这里是我的解决方案：
public static class DateExtensions
{
private static void Swap<T>(ref T one, ref T two)
{
var temp = one;
one = two;
two = temp;
}
public static bool IsFromSameWeek(this DateTime first, DateTime second, DayOfWeek firstDayOfWeek = DayOfWeek.Monday)
{
// sort dates
if (first > second)
{
Swap(ref first, ref second);
}
var daysDiff = (second - first).TotalDays;
if (daysDiff >= 7)
{
return false;
}
const int TotalDaysInWeek = 7;
var adjustedDayOfWeekFirst = (int)first.DayOfWeek + (first.DayOfWeek < firstDayOfWeek ? TotalDaysInWeek : 0);
var adjustedDayOfWeekSecond = (int)second.DayOfWeek + (second.DayOfWeek < firstDayOfWeek ? TotalDaysInWeek : 0);
return adjustedDayOfWeekSecond >= adjustedDayOfWeekFirst;
}
}
如果您不想使用日历类，可以使用此函数：
public static int WeekOfYear(DateTime dt)
{
int startDays = 0;
// first day of the year
DateTime firstJanuary = new DateTime(dt.Year, 1, 1);
if (firstJanuary.DayOfWeek == DayOfWeek.Tuesday)
{
startDays = 1;
}
else if (firstJanuary.DayOfWeek == DayOfWeek.Wednesday)
{
startDays = 2;
}
else if (firstJanuary.DayOfWeek == DayOfWeek.Thursday)
{
startDays = 3;
}
else if (firstJanuary.DayOfWeek == DayOfWeek.Friday)
{
startDays = 4;
}
else if (firstJanuary.DayOfWeek == DayOfWeek.Saturday)
{
startDays = 5;
}
else if (firstJanuary.DayOfWeek == DayOfWeek.Sunday)
{
startDays = 6;
}
if (DateTimeFormatInfo.CurrentInfo.FirstDayOfWeek == DayOfWeek.Sunday)
{
startDays++;
startDays = startDays % 7;
}
return ((dt.DayOfYear + startDays - 1) / 7) + 1;
}
接受的答案对于法国日历和日期为 2022 年 03 月 10 日和 2022 年 10 月 09 日时不起作用。
以下内容适用于我：
public static partial class DateTimeExtensions
{
public static DateTime FirstDayOfWeek(this DateTime dt)
{
var culture = System.Threading.Thread.CurrentThread.CurrentCulture;
var diff = dt.DayOfWeek - culture.DateTimeFormat.FirstDayOfWeek;
if (diff < 0)
{
diff += 7;
}
return dt.AddDays(-diff).Date;
}
public static DateTime LastDayOfWeek(this DateTime dt) =>
dt.FirstDayOfWeek().AddDays(6);
public static DateTime FirstDayOfMonth(this DateTime dt) =>
new DateTime(dt.Year, dt.Month, 1);
public static DateTime LastDayOfMonth(this DateTime dt) =>
dt.FirstDayOfMonth().AddMonths(1).AddDays(-1);
public static DateTime FirstDayOfNextMonth(this DateTime dt) =>
dt.FirstDayOfMonth().AddMonths(1);
public static int GetWeeekNumber(this DateTime dt)
{
CultureInfo culture = System.Threading.Thread.CurrentThread.CurrentCulture;
Calendar myCal = culture.Calendar;
// Gets the DTFI properties required by GetWeekOfYear.
CalendarWeekRule myCWR = culture.DateTimeFormat.CalendarWeekRule;
DayOfWeek myFirstDOW = culture.DateTimeFormat.FirstDayOfWeek;
return myCal.GetWeekOfYear(dt, myCWR, myFirstDOW);
}
public static bool IsInTheSameWeek(this DateTime date1, DateTime date2)
{
return date1.GetWeeekNumber() == date2.GetWeeekNumber();
}
}
使用方法：
item.Week.IsInTheSameWeek(Week)