DateTimeOffset.AddDays(Double) 方法

定义

命名空间:

System

程序集:

System.Runtime.dll

Source:

DateTimeOffset.cs

返回一个新的 DateTimeOffset 对象，它将由整数和小数部分组成的指定天数加到此实例的值上。

public:
 DateTimeOffset AddDays(double days);

public DateTimeOffset AddDays (double days);

member this.AddDays : double -> DateTimeOffset

Public Function AddDays (days As Double) As DateTimeOffset

参数

days

Double

由整数和小数部分组成的天数。 此数值可以是负数也可以是正数。

返回

DateTimeOffset

一个对象，其值为当前的 DateTimeOffset 对象所表示的日期和时间与 days 所表示的天数之和。

例外

ArgumentOutOfRangeException

生成的 DateTimeOffset 值小于 DateTimeOffset.MinValue。

-或-

生成的 DateTimeOffset 值大于 DateTimeOffset.MaxValue。

示例

以下示例使用 AddDays 方法列出 2008 年 3 月星期一（工作周的开始时间）的日期。

DateTimeOffset workDay = new DateTimeOffset(2008, 3, 1, 9, 0, 0,
                   DateTimeOffset.Now.Offset);
int month = workDay.Month;
// Start with the first Monday of the month
if (workDay.DayOfWeek != DayOfWeek.Monday)
{
   if (workDay.DayOfWeek == DayOfWeek.Sunday)
      workDay = workDay.AddDays(1);
   else
      workDay = workDay.AddDays(8 - (int)workDay.DayOfWeek);
}
Console.WriteLine("Beginning of Work Week In {0:MMMM} {0:yyyy}:", workDay);
// Add one week to the current date
do
{
   Console.WriteLine("   {0:dddd}, {0:MMMM}{0: d}", workDay);
   workDay = workDay.AddDays(7);
} while (workDay.Month == month);
// The example produces the following output:
//    Beginning of Work Week In March 2008:
//       Monday, March 3
//       Monday, March 10
//       Monday, March 17
//       Monday, March 24
//       Monday, March 31

let workDay = DateTimeOffset(2008, 3, 1, 9, 0, 0, DateTimeOffset.Now.Offset)
let month = workDay.Month

// Start with the first Monday of the month
let mutable workDay = 
    match workDay.DayOfWeek with
    | DayOfWeek.Monday ->
        workDay
    | DayOfWeek.Sunday ->
        workDay.AddDays 1
    | _ ->
        workDay.AddDays(8. - float workDay.DayOfWeek)

printfn $"Beginning of Work Week In {workDay:MMMM} {workDay:yyyy}:"

// Add one week to the current date
while workDay.Month = month do
    printfn $"   {workDay:dddd}, {workDay:MMMM}{workDay: d}"
    workDay <- workDay.AddDays 7

// The example produces the following output:
//    Beginning of Work Week In March 2008:
//       Monday, March 3
//       Monday, March 10
//       Monday, March 17
//       Monday, March 24
//       Monday, March 31

Dim workDay As New DateTimeOffset(#3/1/2008 9:00AM#, _
                   DateTimeOffset.Now.Offset)
Dim month As Integer = workDay.Month
' Start with the first Monday of the month
If workDay.DayOfWeek <> DayOfWeek.Monday Then
   If workDay.DayOfWeek = DayOfWeek.Sunday Then
      workDay = workDay.AddDays(1)
   Else   
      workDay = workDay.AddDays(8 - CInt(workDay.DayOfWeek))
   End If
End If
Console.WriteLine("Beginning of Work Week In {0:MMMM} {0:yyyy}:", workDay)
' Add one week to the current date 
Do While workDay.Month = month
   Console.WriteLine("   {0:dddd}, {0:MMMM}{0: d}", workDay)
   workDay = workDay.AddDays(7)
Loop        
' The example produces the following output:
'    Beginning of Work Week In March 2008:
'       Monday, March 3
'       Monday, March 10
'       Monday, March 17
'       Monday, March 24
'       Monday, March 31

注解

参数的小 days 数部分是一天的小数部分。 例如，4.5 相当于 4 天 12 小时 0 分钟 0 秒 0 毫秒。

在 .NET 6 及更早版本中， days 参数四舍五入为最接近的毫秒。 在 .NET 7 及更高版本中，将使用 参数的完整Doubledays精度。 但是，由于浮点数学固有的不精确性，生成的精度将有所不同。

注意

此方法返回一个新 DateTimeOffset 对象。 它不会通过将添加到 days 当前对象的日期和时间来修改其值。

DateTimeOffset由于 对象不表示特定时区中的日期和时间，因此该方法AddDays在执行日期和时间算术时不考虑特定时区的调整规则。

将小于一天的时间间隔转换为分数可能会造成精度损失。 如果这是有问题的，可以使用 Add 方法，该方法使你能够在单个方法调用中指定多种类型的时间间隔，并且无需将时间间隔转换为一天的小数部分。