/// <summary>
/// 时间计算类
/// </summary>
public class CalculateTime
{
/// <summary>
/// 计算当天是本周星期几
/// </summary>
/// <param name="now">当前时间</param>
/// <returns></returns>
public static int CaculateWeekDay(DateTime now)
{
int y = now.Year;
int m = now.Month;
int d = now.Day;
if (m == 1) { m = 13; y--; }
if (m == 2) { m = 14; y--; }
int week = (d + 2 * m + 3 * (m + 1) / 5 + y + y / 4 - y / 100 + y / 400) % 7 + 1;
return week;
}
/// <summary>
/// 返回该周星期日的日期。
/// </summary>
/// <param name="now">当前时间</param>
/// <returns></returns>
public static DateTime GetDateOfSunday(DateTime now)
{
int i = CaculateWeekDay(now);
if (i == 7)
{
i = 0;
}
return now.AddDays(-i);
}
/// <summary>
/// 返回上周星期日的日期。
/// </summary>
/// <param name="now">当前时间</param>
/// <returns></returns>
public static DateTime GetDateOfLastSunday(DateTime now)
{
int i = CaculateWeekDay(now);
if (i == 7)
{
i = 0;
}
return now.AddDays(-i).AddDays(-7);
}
/// <summary>
/// 返回该周星期六的日期。
/// </summary>
/// <param name="now">当前时间</param>
/// <returns></returns>
public static DateTime GetDateOfSaturday(DateTime now)
{
int i = CaculateWeekDay(now);
if (i == 7)
{
i = 0;
}
return now.AddDays(-i).AddDays(6);
}
/// <summary>
/// 返回该周星期一的日期。
/// </summary>
/// <param name="now">当前时间</param>
/// <returns></returns>
public static DateTime GetDateOfMonday(DateTime now)
{
int i = CaculateWeekDay(now);
if (i == 7)
{
i = 0;
}
return now.AddDays(-i).AddDays(1);
}
/// <summary>
/// 计算当天所在的周是当年的第几周
/// </summary>
/// <param name="now">当前时间</param>
/// <returns></returns>
public static int GetWeekNumOfYear(DateTime now)
{
int days = now.DayOfYear + (7 - (int)now.DayOfWeek);
return days / 7 + (days % 7 == 0 ? 0 : 1);
}
}