① 获取当月开始日期和结束日期
DateTime currentTime = DateTime.Now; DateTime CurrentMonthStart = DateTime.Parse($"{currentTime.Year}-{currentTime.Month+1}-1");//当月开始日期 int days=System.Threading.Thread.CurrentThread.CurrentUICulture.Calendar.GetDaysInMonth(currentTime.Year, currentTime.Month+1);//当月天数 DateTime CurrentMonthEnd = DateTime.Parse($"{currentTime.Year}-{currentTime.Month+1}-{days}");//当月结束日期
②获取本周开始时间和结束时间
DateTime weekstar = DateTime.Parse(DateTime.Now.AddDays(-(int)DateTime.Now.DayOfWeek + 1).ToString("yyyy-MM-dd 00:00:00")); DateTime weekend = DateTime.Parse(DateTime.Now.AddDays(7 -(int)DateTime.Now.DayOfWeek).ToString("yyyy-MM-dd 23:59:59"));
③ 获取当月第一天和下个月第一天
DateTime DateNow = DateTime.Now; DateTime DateBegin1 = new DateTime(DateNow.Year, DateNow.Month, 1);//当月第一天 //获取下个月第一天 DateTime DateNow1 = DateNow.AddMonths(1); DateTime DateBegin2 = new DateTime(DateNow1.Year, DateNow1.Month, 1);//下个月第一天
④ 计算两个日期之间相差的天数
相关参考网址：https://blog.csdn.net/zht666/article/details/21601403
https://blog.csdn.net/e_wsq/article/details/7278760
TimeSpan ts1 = new TimeSpan(time1.Ticks); TimeSpan ts2 = new TimeSpan(time2.Ticks); TimeSpan ts = time1.Subtract(time2.Now).Duration(); int dateDiff = ts.Days;
⑤今天是星期几
1.string[] Day = new string[] { "星期日", "星期一", "星期二", "星期三", "星期四", "星期五", "星期六" }; string week = Day[Convert.ToInt32(DateTime.Now.DayOfWeek.ToString("d"))].ToString(); lbDay.Text = week; 2. public static string dt; public static string week; dt = DateTime.Today.DayOfWeek.ToString(); switch (dt) { case "Monday": week = "星期一"; break; case "Tuesday": week = "星期二"; break; case "Wednesday": week = "星期三"; break; case "Thursday": week = "星期四"; break; case "Friday": week = "星期五"; break; case "Saturday": week = "星期六"; break; case "Sunday": week = "星期日"; break; } lbDay.Text = week; 3.string Week =System.Globalization.CultureInfo.CurrentCulture.DateTimeFormat.GetDayName(DateTime.Now.DayOfWeek);
⑥查询某月某周几的日期
foreach (MaintenanceDutyPsersonDto item in maintenanceDuty) { string yearandmonth = item.DutyDate.ToString("yyyy-MM"); int year = item.DutyDate.Year; int month = item.DutyDate.Month; int d = DateTime.DaysInMonth(year, month); //获取指定年月的天数 if (item.Dutymodel == "周")//按周排班 { string[] weeks = item.weeks; List<string> datelist1 = new List<string>(); for (int i = 0; i < weeks.Length; i++) { switch (weeks[i]) { case "周一": for (int a = 1; a <= d; a++) { DateTime dt = new DateTime(year, month, a); if (dt.DayOfWeek == DayOfWeek.Monday) { datelist1.Add(dt.ToShortDateString()); } } break; case "周二": for (int a = 1; a <= d; a++) { DateTime dt = new DateTime(year, month, a); if (dt.DayOfWeek == DayOfWeek.Tuesday) { datelist1.Add(dt.ToShortDateString()); } } break; case "周三": for (int a = 1; a <= d; a++) { DateTime dt = new DateTime(year, month, a); if (dt.DayOfWeek == DayOfWeek.Wednesday) { datelist1.Add(dt.ToShortDateString()); } } break; case "周四": for (int a = 1; a <= d; a++) { DateTime dt = new DateTime(year, month, a); if (dt.DayOfWeek == DayOfWeek.Thursday) { datelist1.Add(dt.ToShortDateString()); } } break; case "周五": for (int a = 1; a <= d; a++) { DateTime dt = new DateTime(year, month, a); if (dt.DayOfWeek == DayOfWeek.Friday) { datelist1.Add(dt.ToShortDateString()); } } break; case "周六": for (int a = 1; a <= d; a++) { DateTime dt = new DateTime(year, month, a); if (dt.DayOfWeek == DayOfWeek.Saturday) { datelist1.Add(dt.ToShortDateString()); } } break; case "周日": for (int a = 1; a <= d; a++) { DateTime dt = new DateTime(year, month, a); if (dt.DayOfWeek == DayOfWeek.Sunday) { datelist1.Add(dt.ToShortDateString()); } } break; default: break; } }
⑦ 获取某段日期范围内的所有日期
/// <summary> /// 获取某段日期范围内的所有日期，以数组形式返回 /// </summary> /// <param name="dt1">开始日期</param> /// <param name="dt2">结束日期</param> /// <returns></returns> private DateTime[] GetAllDays(DateTime dt1, DateTime dt2) { List<DateTime> listDays = new List<DateTime>(); DateTime dtDay = new DateTime(); for (dtDay = dt1; dtDay.CompareTo(dt2) <= 0; dtDay = dtDay.AddDays(1)) { listDays.Add(dtDay); } return listDays.ToArray(); }
⑧判断某个日期是否在某段日期范围内
/// <summary> /// 获取某段日期范围内的所有日期，以字符串形式返回 /// </summary> /// <param name="startDate">开始日期</param> /// <param name="endDate">结束日期</param> /// <returns></returns> protected string GetDate(DateTime startDate, DateTime endDate) { string result = string.Empty; for (DateTime temp = startDate.ToShortDateString(); temp <= endDate.ToShortDateString(); temp = temp.AddDays(1)) { if (result == string.Empty) { result = temp.ToString(); } else { result += "," + temp.ToString(); } } return result; }
⑨ C#时间类型 DateTime? 赋空值 关于datetime类型的DBNull判断
public DateTime? SubTime { get; set; } //日期类型判断是否为null 用nullable这个泛型结构体 m.SubTime=dr["subtime"]==DBNull.Value?new Nullable<DateTime>():Convert.ToDateTime(dr["subtime"])
⑩合集
/今天 DateTime.Now.Date.ToShortDateString(); //昨天，就是今天的日期减一 DateTime.Now.AddDays(-1).ToShortDateString(); //明天，同理，加一 DateTime.Now.AddDays(1).ToShortDateString(); //本周(要知道本周的第一天就得先知道今天是星期几，从而得知本周的第一天就是几天前的那一天，要注意的是这里的每一周是从周日始至周六止 DateTime.Now.AddDays(Convert.ToDouble((0 - Convert.ToInt16(DateTime.Now.DayOfWeek)))).ToShortDateString(); DateTime.Now.AddDays(Convert.ToDouble((6 - Convert.ToInt16(DateTime.Now.DayOfWeek)))).ToShortDateString(); //如果你还不明白，再看一下中文显示星期几的方法就应该懂了 //由于DayOfWeek返回的是数字的星期几，我们要把它转换成汉字方便我们阅读，有些人可能会用switch来一个一个地对照，其实不用那么麻烦的 string[] Day = new string[] { "星期日", "星期一", "星期二", "星期三", "星期四", "星期五", "星期六" }; Day[Convert.ToInt16(DateTime.Now.DayOfWeek)]; //上周，同理，一个周是7天，上周就是本周再减去7天，下周也是一样 DateTime.Now.AddDays(Convert.ToDouble((0 - Convert.ToInt16(DateTime.Now.DayOfWeek))) - 7).ToShortDateString(); DateTime.Now.AddDays(Convert.ToDouble((6 - Convert.ToInt16(DateTime.Now.DayOfWeek))) - 7).ToShortDateString(); //下周 DateTime.Now.AddDays(Convert.ToDouble((0 - Convert.ToInt16(DateTime.Now.DayOfWeek))) + 7).ToShortDateString(); DateTime.Now.AddDays(Convert.ToDouble((6 - Convert.ToInt16(DateTime.Now.DayOfWeek))) + 7).ToShortDateString(); //本月,很多人都会说本月的第一天嘛肯定是1号，最后一天就是下个月一号再减一天。当然这是对的 //一般的写法 DateTime.Now.Year.ToString() + DateTime.Now.Month.ToString() + "1"; //第一天 DateTime.Parse(DateTime.Now.Year.ToString() + DateTime.Now.Month.ToString() + "1").AddMonths(1).AddDays(-1).ToShortDateString();//最后一天 //巧用C#里ToString的字符格式化更简便 DateTime.Now.ToString("yyyy-MM-01"); DateTime.Parse(DateTime.Now.ToString("yyyy-MM-01")).AddMonths(1).AddDays(-1).ToShortDateString(); //上个月，减去一个月份 DateTime.Parse(DateTime.Now.ToString("yyyy-MM-01")).AddMonths(-1).ToShortDateString(); DateTime.Parse(DateTime.Now.ToString("yyyy-MM-01")).AddDays(-1).ToShortDateString(); //下个月，加去一个月份 DateTime.Parse(DateTime.Now.ToString("yyyy-MM-01")).AddMonths(1).ToShortDateString(); DateTime.Parse(DateTime.Now.ToString("yyyy-MM-01")).AddMonths(2).AddDays(-1).ToShortDateString(); //7天后 DateTime.Now.Date.ToShortDateString(); DateTime.Now.AddDays(7).ToShortDateString(); //7天前 DateTime.Now.AddDays(-7).ToShortDateString(); DateTime.Now.Date.ToShortDateString(); //本年度，用ToString的字符格式化我们也很容易地算出本年度的第一天和最后一天 DateTime.Parse(DateTime.Now.ToString("yyyy-01-01")).ToShortDateString(); DateTime.Parse(DateTime.Now.ToString("yyyy-01-01")).AddYears(1).AddDays(-1).ToShortDateString(); //上年度，不用再解释了吧 DateTime.Parse(DateTime.Now.ToString("yyyy-01-01")).AddYears(-1).ToShortDateString(); DateTime.Parse(DateTime.Now.ToString("yyyy-01-01")).AddDays(-1).ToShortDateString(); //下年度 DateTime.Parse(DateTime.Now.ToString("yyyy-01-01")).AddYears(1).ToShortDateString(); DateTime.Parse(DateTime.Now.ToString("yyyy-01-01")).AddYears(2).AddDays(-1).ToShortDateString(); //本季度，很多人都会觉得这里难点，需要写个长长的过程来判断。其实不用的，我们都知道一年四个季度，一个季度三个月 //首先我们先把日期推到本季度第一个月，然后这个月的第一天就是本季度的第一天了 DateTime.Now.AddMonths(0 - ((DateTime.Now.Month - 1) % 3)).ToString("yyyy-MM-01"); //同理，本季度的最后一天就是下季度的第一天减一 DateTime.Parse(DateTime.Now.AddMonths(3 - ((DateTime.Now.Month - 1) % 3)).ToString("yyyy-MM-01")).AddDays(-1).ToShortDateString(); //下季度 DateTime.Now.AddMonths(3 - ((DateTime.Now.Month - 1) % 3)).ToString("yyyy-MM-01"); DateTime.Parse(DateTime.Now.AddMonths(6 - ((DateTime.Now.Month - 1) % 3)).ToString("yyyy-MM-01")).AddDays(-1).ToShortDateString(); //上季度 DateTime.Now.AddMonths(-3 - ((DateTime.Now.Month - 1) % 3)).ToString("yyyy-MM-01"); DateTime.Parse(DateTime.Now.AddMonths(0 - ((DateTime.Now.Month - 1) % 3)).ToString("yyyy-MM-01")).AddDays(-1).ToShortDateString();