public  void Init()
    {
    
     
     string  Month =GetDateTimeWeekFirstDayMon();
     string Day = GetDateTimeWeekLastDaySun();
       day.text =Month+" - "+Day;
    }

    /// <summary>
    /// 获取本周的第一天    周一为第一天
    /// </summary>
    /// <returns></returns>
    private string GetDateTimeWeekFirstDayMon()
    {
    
    
        //计算机上当前的时间
        DateTime nowTime = DateTime.Now;
        //获取当前日期的星期    周日是0   周一是1
        int weeknow = Convert.ToInt32(nowTime.DayOfWeek);
        weeknow = (weeknow == 0 ? (7 - 1) : (weeknow - 1));//如果今天是周日  获取往前推六天的日期
        int daydiff = (-1) * weeknow;//得到往前推的天数
        DateTime FirstDay = nowTime.AddDays(daydiff);//获取往前推的日期
        
        string timeDay = FirstDay.Month +"."+   FirstDay.Date.Day ; //获取往前推的日期的月份和日数；
        return timeDay;
    }

    /// <summary>
    /// 获取本周的最后一天 周日为最后一天
    /// </summary>
    /// <returns></returns>
    private string GetDateTimeWeekLastDaySun()
    {
    
    
        DateTime nowTime = DateTime.Now;
        int lastWeekDay = Convert.ToInt32(nowTime.DayOfWeek);//获取当前日期的星期
        lastWeekDay = lastWeekDay == 0 ? (7 - lastWeekDay) : lastWeekDay;//往后推算日期
        int lastWeekDiff = (7 - lastWeekDay);//得到往后推算日期的天数

        //本周最后一天  
        DateTime LastDay = nowTime.AddDays(lastWeekDiff);
        string timeDay = LastDay.Month +"."+   LastDay.Date.Day ; 
        return timeDay;
    }

今天日期是9月23 星期三