C# DateTime应用

一时失言乱红尘 2023-10-08 11:08 4阅读 0赞

1、获取当月第一天0时0分0秒

DateTime.Now.AddDays(1 - DateTime.Now.Day);

Convet.ToDateTime(DateTime.Now.ToString("yyyy-MM-01"));

2、获取当月最后一天23时59分59秒：

DateTime.Now.AddDays(1 - DateTime.Now.Day).AddMonths(1).AddSeconds(-1);

Convet.ToDateTime(DateTime.Now.AddMonths(1).ToString("yyyy-MM-01")).AddSeconds(-1);

3、获取当月后一月第一天0时0分0秒

DateTime.Now.AddDays(1 - DateTime.Now.Day).AddMonths(1)

Convet.ToDateTime(DateTime.Now.AddMonths(1).ToString("yyyy-MM-01"));

4、获取当月前一月第一天0时0分0秒

DateTime.Now.AddDays(1 - DateTime.Now.Day).AddMonths(-1)

Convet.ToDateTime(DateTime.Now.AddMonths(-1).ToString("yyyy-MM-01"));

5、判断时间是否在指定月份内

public bool HasDomain(DateTime testTime,DateTime domain){
    
        DateTime startTime = domain.AddDays(1 - domain.Day);//当前月份第一天2019/12/1 00：00：00
        DateTime endTime = domain.AddDays(1 - domain.Day).AddMonths(1);//当前月份后一月的第一天2020/1/1 00：00：00
        if(testTime>=startTime&&testTime<endTime){
            return true;
        }else{
            return false;   
        }
    }

6、获取指定日期是一年中的第几周

public int WeekOfYear(DateTime dtime){
        int weeknum = 0;
        DateTime tmpdate = DateTime.Parse(dtime.Year.ToString() + "-1" + "-1");
        DayOfWeek firstweek = tmpdate.DayOfWeek;
        int i = dtime.DayOfYear - 1 + (int)firstweek;
        weeknum = i / 7;
        if (i > 0) weeknum++;
        return weeknum;
    }

7、获取指定日期的星期一

public DateTime GetMonday(DateTime dateTime){
        int monDiff=dateTime.DayOfWeek-DayOfWeek.Monday;
        monDiff = monDiff == -1 ? 6 : monDiff;
        DateTime monTime = dTimedateTimeAddDays(-monDiff);
        return monTime;
    }

8、获取指定日期的星期天

public DateTime GetSunday(DateTime dateTime){
        int sunDiff = dTime.DayOfWeek - DayOfWeek.Sunday;
        sunDiff = sunDiff !=0 ? 7-sunDiff : sunDiff;
        DateTime sunTime = dTime.AddDays(sunDiff);
    }