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  • c# 获取某日期所在周的第一天和最后一天

    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Text;
    
    namespace WyfClass
    {
    public class tools
    {
    /// <summary>
    /// 得到本周第一天(以星期天为第一天)
    /// </summary>
    /// <param name="datetime"></param>
    /// <returns></returns>
    public DateTime GetWeekFirstDaySun(DateTime datetime)
    {
        //星期天为第一天
        int weeknow = Convert.ToInt32(datetime.DayOfWeek);
        int daydiff = (-1) * weeknow;
    
        //本周第一天
        string FirstDay = datetime.AddDays(daydiff).ToString("yyyy-MM-dd");
        return Convert.ToDateTime(FirstDay);
    }
    
    /// <summary>
    /// 得到本周第一天(以星期一为第一天)
    /// </summary>
    /// <param name="datetime"></param>
    /// <returns></returns>
    public DateTime GetWeekFirstDayMon(DateTime datetime)
    {
        //星期一为第一天
        int weeknow = Convert.ToInt32(datetime.DayOfWeek);
    
        //因为是以星期一为第一天,所以要判断weeknow等于0时,要向前推6天。
        weeknow = (weeknow == 0 ? (7 - 1) : (weeknow - 1));
        int daydiff = (-1) * weeknow;
    
        //本周第一天
        string FirstDay = datetime.AddDays(daydiff).ToString("yyyy-MM-dd");
        return Convert.ToDateTime(FirstDay);
    }
    
    /// <summary>
    /// 得到本周最后一天(以星期六为最后一天)
    /// </summary>
    /// <param name="datetime"></param>
    /// <returns></returns>
    public DateTime GetWeekLastDaySat(DateTime datetime)
    {
        //星期六为最后一天
        int weeknow = Convert.ToInt32(datetime.DayOfWeek);
        int daydiff = (7 - weeknow) - 1;
    
        //本周最后一天
        string LastDay = datetime.AddDays(daydiff).ToString("yyyy-MM-dd");
        return Convert.ToDateTime(LastDay);
    }
    
    /// <summary>
    /// 得到本周最后一天(以星期天为最后一天)
    /// </summary>
    /// <param name="datetime"></param>
    /// <returns></returns>
    public DateTime GetWeekLastDaySun(DateTime datetime)
    {
        //星期天为最后一天
        int weeknow = Convert.ToInt32(datetime.DayOfWeek);
        weeknow = (weeknow == 0 ? 7 : weeknow);
        int daydiff = (7 - weeknow);
    
        //本周最后一天
        string LastDay = datetime.AddDays(daydiff).ToString("yyyy-MM-dd");
        return Convert.ToDateTime(LastDay);
    }
    }
    }
    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Text;
    
    namespace WyfClass
    {
    public class tools
    {
    /// <summary>
    /// 得到本周第一天(以星期天为第一天)
    /// </summary>
    /// <param name="datetime"></param>
    /// <returns></returns>
    public DateTime GetWeekFirstDaySun(DateTime datetime)
    {
        //星期天为第一天
        int weeknow = Convert.ToInt32(datetime.DayOfWeek);
        int daydiff = (-1) * weeknow;
    
        //本周第一天
        string FirstDay = datetime.AddDays(daydiff).ToString("yyyy-MM-dd");
        return Convert.ToDateTime(FirstDay);
    }
    
    /// <summary>
    /// 得到本周第一天(以星期一为第一天)
    /// </summary>
    /// <param name="datetime"></param>
    /// <returns></returns>
    public DateTime GetWeekFirstDayMon(DateTime datetime)
    {
        //星期一为第一天
        int weeknow = Convert.ToInt32(datetime.DayOfWeek);
    
        //因为是以星期一为第一天,所以要判断weeknow等于0时,要向前推6天。
        weeknow = (weeknow == 0 ? (7 - 1) : (weeknow - 1));
        int daydiff = (-1) * weeknow;
    
        //本周第一天
        string FirstDay = datetime.AddDays(daydiff).ToString("yyyy-MM-dd");
        return Convert.ToDateTime(FirstDay);
    }
    
    /// <summary>
    /// 得到本周最后一天(以星期六为最后一天)
    /// </summary>
    /// <param name="datetime"></param>
    /// <returns></returns>
    public DateTime GetWeekLastDaySat(DateTime datetime)
    {
        //星期六为最后一天
        int weeknow = Convert.ToInt32(datetime.DayOfWeek);
        int daydiff = (7 - weeknow) - 1;
    
        //本周最后一天
        string LastDay = datetime.AddDays(daydiff).ToString("yyyy-MM-dd");
        return Convert.ToDateTime(LastDay);
    }
    
    /// <summary>
    /// 得到本周最后一天(以星期天为最后一天)
    /// </summary>
    /// <param name="datetime"></param>
    /// <returns></returns>
    public DateTime GetWeekLastDaySun(DateTime datetime)
    {
        //星期天为最后一天
        int weeknow = Convert.ToInt32(datetime.DayOfWeek);
        weeknow = (weeknow == 0 ? 7 : weeknow);
        int daydiff = (7 - weeknow);
    
        //本周最后一天
        string LastDay = datetime.AddDays(daydiff).ToString("yyyy-MM-dd");
        return Convert.ToDateTime(LastDay);
    }
    }
    }
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  • 原文地址:https://www.cnblogs.com/bennylam/p/4181354.html
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