51.C# DateTime类

摘要

时间日期操作类，包含DateTime可处理日期和时间的结构。要在C#中使用日期和时间，请使用 new 关键字创建 DateTime 结构的对象。

正文

方法

获取时间

static void Main(string[] args)
{
    Console.WriteLine(System.DateTime.Now);        // 当前本地时间 (年月日时分秒)
    Console.WriteLine(System.DateTime.UtcNow);     // 当前世界时间 (年月日时分秒)
    Console.WriteLine(System.DateTime.Now.Year);   // 当前时间 (年)
    Console.WriteLine(System.DateTime.Now.Month);  // 当前时间 (月)
    Console.WriteLine(System.DateTime.Now.Day);    // 当前时间 (日)
    Console.WriteLine(System.DateTime.Now.Hour);   // 当前时间 (时)
    Console.WriteLine(System.DateTime.Now.Minute); // 当前时间 (分)
    Console.WriteLine(System.DateTime.Now.Second); // 当前时间 (秒)
}

字符串转时间

static void Main(string[] args)
{

    DateTime date1 = new DateTime();//1/1/0001 12:00:00 AM —— 默认构造函数
    DateTime date2 = new DateTime(2023, 1, 6, 6, 6, 6); //1/6/2023 6:06:06 AM —— 初始化 年、月、日、时、分、秒
    Console.WriteLine(date2.ToString("yyyyMMddHH:mm:ss")); //2023060606:06:06 
    Console.WriteLine(date2.ToString("yyyy-MM-dd-HH-mm-ss"));//2023-06-06-06-06-06 —— DateTime.ToString(String)使用自定义方式格式化日期字符串

}

DateTime d1 = DateTime.Now;
Console.WriteLine(d1.Date);
Console.WriteLine(d1.Day);
Console.WriteLine(d1.DayOfWeek);
Console.WriteLine(d1.DayOfYear);
Console.WriteLine(d1.AddDays(10));
Console.WriteLine(d1.AddDays(-10));
Console.WriteLine(d1.AddHours(6));
Console.WriteLine(d1.AddSeconds(10));
DateTime dt1 = DateTime.Now;
**DateTime dt2 = new DateTime(2021, 6, 1);
TimeSpan ts = dt2 - dt1;**
Console.WriteLine("间隔的天数为{0}天", ts.Days);

//计算某年某月的天数
int days = DateTime.DaysInMonth(2017, 2);
Console.WriteLine(days.ToString());
//本月的天数
int daysInMonth = DateTime.DaysInMonth(DateTime.Now.Year, DateTime.Now.Month);
Console.WriteLine(daysInMonth.ToString());
//本年的天数 是否是闰年          
int daysInYear = DateTime.IsLeapYear(DateTime.Now.Year) ? 366 : 365;
Console.WriteLine(daysInYear.ToString());
//本月第一天
DateTime firstDayInMonth = new DateTime(DateTime.Now.Year, DateTime.Now.Month, 1);
Console.WriteLine(firstDayInMonth.ToString());
//本月的最后一天
DateTime lastDayInMonth = new DateTime(DateTime.Now.Year, DateTime.Now.Month, 1).AddMonths(1).AddDays(-1);
Console.WriteLine(lastDayInMonth.ToString());
//得到星期几 星期天为7
int dayOfWeek = Convert.ToInt32(DateTime.Now.DayOfWeek) < 1 ? 7 : Convert.ToInt32(DateTime.Now.DayOfWeek);
Console.WriteLine(dayOfWeek.ToString());
//本季度第一天
DateTime firsyDayInQuarter = new DateTime(DateTime.Now.Year, DateTime.Now.Month - (DateTime.Now.Month - 1) % 3, 1);
Console.WriteLine(firsyDayInQuarter.ToString());
//本季度最后一天
DateTime lastDayInQuarter = firsyDayInQuarter.AddMonths(3).AddDays(-1);
Console.WriteLine(lastDayInQuarter.ToString());