C#日期操作-星期(week)相关-YES开发框架网

根据年份和周数(weekIndex)，获取星期(week)的开始日期和结束日期

/// <summary>
/// 根据年份和星期周数，获得星期的日期范围
/// </summary>
/// <param name="year">年份</param>
/// <param name="weekIndex">星期的周数，年度第几周</param>
/// <param name="firstDayOfWeek">表示一周的第一天的星期值(枚举值)</param>
/// <returns>日期数组，[开始日期，结束日期]</returns>
public DateTime[] GetDateRange(int year, int weekIndex, DayOfWeek firstDayOfWeek)
{
    DateTime time = DateTime.Parse(year + "-01-01");
    while (time.DayOfWeek != firstDayOfWeek)
    {
        time = time.AddDays(1);
    }
    DateTime time1 = time.AddDays((weekIndex - 1) * 7);
    DateTime time2 = time1.AddDays(6);
    return new DateTime[] { time1, time2 };
}

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根据日期，获得当前星期(week)的第一天日期

/// <summary>
/// 根据日期获得星期的第一天
/// </summary>
/// <param name="date">日期</param>
/// <param name="firstDayOfWeek">表示一周的第一天的星期值(枚举值)</param>
/// <returns>星期的第一天</returns>
public DateTime GetWeekFirstDay(DateTime date,DayOfWeek firstDayOfWeek)
{
    while (date.DayOfWeek != firstDayOfWeek)
    {
        date=date.AddDays(-1);
    }

    return date;
}

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根据日期，获得当前星期(week)的最后一天日期

/// <summary>
/// 根据日期获得星期的最后一天
/// </summary>
/// <param name="date">日期</param>
/// <param name="firstDayOfWeek">表示一周的第一天的星期值(枚举值)</param>
/// <returns>星期的最后一天</returns>
public DateTime GetWeekLastDay(DateTime date, DayOfWeek firstDayOfWeek)
{
    DayOfWeek lastDayOfWeek = (DayOfWeek)((((int)firstDayOfWeek - 1) + 7) % 7);
    while (date.DayOfWeek != lastDayOfWeek)
    {
        date = date.AddDays(1);
    }

    return date;
}

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根据第一天的星期枚举，来获得星期(week)的最后一天枚举值

/// <summary>
/// 获得一个星期的最后星期值(枚举值)
/// </summary>
/// <param name="firstDayOfWeek"></param>
/// <returns></returns>
public DayOfWeek GetLastDayOfWeek(DayOfWeek firstDayOfWeek)
{
    int lastDayOfWeek = (((int)firstDayOfWeek - 1) + 7) % 7;
    return (DayOfWeek)lastDayOfWeek;
}

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获得日期为当年的第几周

/// <summary>
/// 获得当前日期是一年中的第几个星期
/// </summary>
/// <param name="date">日期</param>
/// <param name="rule">定义日历周的枚举值。</param>
/// <param name="firstDayOfWeek">表示一周的第一天的星期值(枚举值)</param>
/// <returns>周数</returns>
public int GetWeekOfYear(DateTime date, System.Globalization.CalendarWeekRule rule, DayOfWeek firstDayOfWeek)
{
    System.Globalization.GregorianCalendar gc = new System.Globalization.GregorianCalendar();
    int weekIndex = gc.GetWeekOfYear(date, rule, firstDayOfWeek);
    return weekIndex;
}

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1. 当年第一天所在的日期为第一周

/// <summary>
/// 获得当前日期是一年中的第几个星期
/// 指示年的第一周从该年的第一天开始，到所指定周的下一个首日前结束。值为 0。
/// </summary>
/// <param name="date">日期</param>
/// <param name="firstDayOfWeek">表示一周的第一天的星期值(枚举值)</param>
/// <returns>周数</returns>
public int GetWeekOfYearByFirstDay(DateTime date, DayOfWeek firstDayOfWeek)
{
    System.Globalization.GregorianCalendar gc = new System.Globalization.GregorianCalendar();
    int weekIndex = gc.GetWeekOfYear(date, System.Globalization.CalendarWeekRule.FirstDay, firstDayOfWeek);
    return weekIndex;
}

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2. 日期从周首日开始匹配，整个星期的日期都在当年才算

/// <summary>
/// 获得当前日期是一年中的第几个星期
/// 指示年的第一周从所指定周首日的第一个匹配项开始，可以是年的第一天或其后某一天。值为 1。
/// </summary>
/// <param name="date">日期</param>
/// <param name="firstDayOfWeek">表示一周的第一天的星期值(枚举值)</param>
/// <returns>周数</returns>
public int GetWeekOfYearByFirstFullWeek(DateTime date, DayOfWeek firstDayOfWeek)
{
    System.Globalization.GregorianCalendar gc = new System.Globalization.GregorianCalendar();
    int weekIndex = gc.GetWeekOfYear(date, System.Globalization.CalendarWeekRule.FirstFullWeek, firstDayOfWeek);
    return weekIndex;
}

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3. 日期所在周需要报含4天或更多天

开始日期所在周本年度总天数小于4天	开始日期所在周本年度总天数大于4天或4天以上

/// <summary>
/// 获得当前日期是一年中的第几个星期
/// 指示年的第一周是第一个在指定的周首日前包含四天或更多天的周。值为 2。
/// </summary>
/// <param name="date">日期</param>
/// <param name="firstDayOfWeek">表示一周的第一天的星期值(枚举值)</param>
/// <returns>周数</returns>
public int GetWeekOfYearByFirstFourDayWeek(DateTime date, DayOfWeek firstDayOfWeek)
{
    System.Globalization.GregorianCalendar gc = new System.Globalization.GregorianCalendar();
    int weekIndex = gc.GetWeekOfYear(date, System.Globalization.CalendarWeekRule.FirstFourDayWeek, firstDayOfWeek);
    return weekIndex;
}

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