DateTime.AddDays(Double) DateTime.AddDays(Double) DateTime.AddDays(Double) DateTime.AddDays(Double) Method

定义

返回一个新的 DateTime,它将指定的天数加到此实例的值上。Returns a new DateTime that adds the specified number of days to the value of this instance.

public:
 DateTime AddDays(double value);
public DateTime AddDays (double value);
member this.AddDays : double -> DateTime
Public Function AddDays (value As Double) As DateTime

参数

value
Double Double Double Double

由整数和小数部分组成的天数。A number of whole and fractional days. value 参数可以是负数也可以是正数。The value parameter can be negative or positive.

返回

一个对象,其值是此实例所表示的日期和时间与 value 所表示的天数之和。An object whose value is the sum of the date and time represented by this instance and the number of days represented by value.

异常

示例

下面的示例使用AddDays方法来确定当前日期之后36天中的第几天。The following example uses the AddDays method to determine the day of the week 36 days after the current date.

using namespace System;

int main()
{
   // Calculate what day of the week is 36 days from this instant.
   DateTime today = System::DateTime::Now;
   DateTime answer = today.AddDays( 36 );
   Console::WriteLine("Today: {0:dddd}", today);
   Console::WriteLine("36 days from today: {0:dddd}", answer);
}
// The example displays output like the following:
//       Today: Wednesday
//       36 days from today: Thursday
using System;

class Class1
{
	static void Main()
	{
		DateTime today = DateTime.Now;
		DateTime answer = today.AddDays(36);
        Console.WriteLine("Today: {0:dddd}", today);
        Console.WriteLine("36 days from today: {0:dddd}", answer);
	}
}
// The example displays output like the following:
//       Today: Wednesday
//       36 days from today: Thursday
Class Class1
   Public Shared Sub Main()
      Dim today As System.DateTime
      Dim answer As System.DateTime

      today = System.DateTime.Now
      answer = today.AddDays(36)

      Console.WriteLine("Today: {0:dddd}", today)
      Console.WriteLine("36 days from today: {0:dddd}", answer)
   End Sub
End Class
' The example displays output like the following:
'       Today: Wednesday
'       36 days from today: Thursday

注解

此方法不更改此DateTime的值。This method does not change the value of this DateTime. 相反,它会返回一个DateTime新的,其值为此操作的结果。Instead, it returns a new DateTime whose value is the result of this operation.

的小数部分value是一天中的小数部分。The fractional part of value is the fractional part of a day. 例如,4.5 等效于4天,12小时,0分钟,0秒,0毫秒,0刻度。For example, 4.5 is equivalent to 4 days, 12 hours, 0 minutes, 0 seconds, 0 milliseconds, and 0 ticks.

value参数舍入为最接近的毫秒。The value parameter is rounded to the nearest millisecond.

AddDays方法会在执行日期算法时考虑闰年和月份中的天数。The AddDays method takes into account leap years and the number of days in a month when performing date arithmetic.

适用于

另请参阅