//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= newstring[] { "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，相信你们都知道了。。。。收工
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();
//定义变量
private static DateTime currentDateTime; //当前时间
private static DateTime lastDateTime; //昨天时间
private static DateTime nextDateTime; //明天时间
private static int currentDayOfWeek; //今天星期几
private static int lastDayOfWeek; //昨天星期几
private static int nextDayOfWeek; //明天星期几
private static DateTime currentStartWeek; //本周周一
private static DateTime currentEndWeek; //本周周日
private static DateTime currentStartMonth; //本月月初
private static DateTime currentEndMonth; //本月月末
private static DateTime currentStartQuarter; //本季度初
private static DateTime currentEndQuarter; //本季度末
private static DateTime currentStartYear; //今年年初
private static DateTime currentEndYear; //今年年末
private static DateTime lastStartWeek; //上周周一
private static DateTime lastEndWeek; //上周周日
private static DateTime lastStartMonth; //上月月初
private static DateTime lastEndMonth; //上月月末
private static DateTime lastStartQuarter; //上季度初
private static DateTime lastEndQuarter; //上季度末
private static DateTime lastStartYear; //去年年初
private static DateTime lastEndYear; //去年年末
private static DateTime nextStartWeek; //下周周一
private static DateTime nextEndWeek; //下周周日
private static DateTime nextStartMonth; //下月月初
private static DateTime nextEndMonth; //下月月末
private static DateTime nextStartQuarter; //下季度初
private static DateTime nextEndQuarter; //下季度末
private static DateTime nextStartYear; //明年年初
private static DateTime nextEndYear; //明年年末
//计算变量
currentDateTime = DateTime.Now; //当前时间
lastDateTime = DateTime.Now.AddDays(-1); //昨天时间
nextDateTime = DateTime.Now.AddDays(1); //明天时间
currentDayOfWeek = Convert.ToInt32(currentDateTime.DayOfWeek.ToString("d")); //今天星期几
currentDayOfWeek = Convert.ToInt32(lastDateTime.DayOfWeek.ToString("d")); //昨天星期几
currentDayOfWeek = Convert.ToInt32(nextDateTime.DayOfWeek.ToString("d")); //明天星期几
currentStartWeek = currentDateTime.AddDays(1 - ((currentDayOfWeek == 0) ? 7 : currentDayOfWeek)); //本周周一
currentEndWeek = currentStartWeek.AddDays(6); //本周周日
lastStartWeek = currentStartWeek.AddDays(-7); //上周周一
lastEndWeek = currentEndWeek.AddDays(-7); //上周周日
nextStartWeek = currentStartWeek.AddDays(7); //下周周一
nextEndWeek = currentEndWeek.AddDays(7); //下周周日
currentStartMonth = currentDateTime.AddDays(1 - currentDateTime.Day); //本月月初
currentEndMonth = currentStartMonth.AddMonths(1).AddDays(-1); //本月月末
lastStartMonth = currentStartMonth.AddMonths(-1); //上月月初
lastEndMonth = currentStartMonth.AddDays(-1); //上月月末
nextStartMonth = currentEndMonth.AddDays(1); //下月月初
nextEndMonth = nextStartMonth.AddMonths(1).AddDays(-1); //下月月末
currentStartQuarter = currentDateTime.AddMonths(0 - (currentDateTime.Month - 1) % 3).AddDays(1 - currentDateTime.Day); //本季度初
currentEndQuarter = currentStartQuarter.AddMonths(3).AddDays(-1); //本季度末
lastStartQuarter = currentStartQuarter.AddMonths(-3); //上季度初
lastEndQuarter = currentStartQuarter.AddDays(-1); //上季度末
nextStartQuarter = currentEndQuarter.AddDays(1); //下季度初
nextEndQuarter = nextStartQuarter.AddMonths(3).AddDays(-1); //下季度末
//年度运算
currentStartYear = new DateTime(currentDateTime.Year, 1, 1); //今年年初
currentEndYear = new DateTime(currentDateTime.Year, 12, 31); //今年年末
lastStartYear = currentStartYear.AddYears(-1); //去年年初
lastEndYear = currentEndYear.AddYears(-1); //去年年末
nextStartYear = currentStartYear.AddYears(1); //明年年初
nextEndYear = currentEndYear.AddYears(1); //明年年末
/// <summary>
/// 返回星期几字符串函数
/// </summary>
/// <param name="myDateTime"></param>
/// <returns></returns>
private string GetWeekDayName(DateTime myDateTime)
{
string week = "";
//获取当前日期是星期几
string dt = myDateTime.DayOfWeek.ToString();
//根据取得的星期英文单词返回汉字
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;
}
return week;
}
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，相信你们都知道了。。。。收工
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();
原文：http://blog.csdn.net/hefeng_aspnet/article/details/6616650