# DateTime.DayOfYear プロパティ

## 定義

このインスタンスで表される年間積算日を取得します。

public:
property int DayOfYear { int get(); };
public int DayOfYear { get; }
member this.DayOfYear : int
Public ReadOnly Property DayOfYear As Integer

#### プロパティ値

1 から 366 までの間の積算日。

## 例

using System;

public class Example
{
public static void Main()
{
DateTime dec31 = new DateTime(2010, 12, 31);
for (int ctr = 0; ctr <= 10; ctr++) {
DateTime dateToDisplay = dec31.AddYears(ctr);
Console.WriteLine("{0:d}: day {1} of {2} {3}", dateToDisplay,
dateToDisplay.DayOfYear,
dateToDisplay.Year,
DateTime.IsLeapYear(dateToDisplay.Year) ?
"(Leap Year)" : "");
}
}
}
// The example displays the following output:
//       12/31/2010: day 365 of 2010
//       12/31/2011: day 365 of 2011
//       12/31/2012: day 366 of 2012 (Leap Year)
//       12/31/2013: day 365 of 2013
//       12/31/2014: day 365 of 2014
//       12/31/2015: day 365 of 2015
//       12/31/2016: day 366 of 2016 (Leap Year)
//       12/31/2017: day 365 of 2017
//       12/31/2018: day 365 of 2018
//       12/31/2019: day 365 of 2019
//       12/31/2020: day 366 of 2020 (Leap Year)

open System

let dec31 = DateTime(2010, 12, 31)
for i = 0 to 10 do
let dateToDisplay = dec31.AddYears i
let leap = if DateTime.IsLeapYear dateToDisplay.Year then "(Leap Year)" else ""
printfn \$"{dateToDisplay:d}: day {dateToDisplay.DayOfYear} of {dateToDisplay.Year} {leap}"

// The example displays the following output:
//       12/31/2010: day 365 of 2010
//       12/31/2011: day 365 of 2011
//       12/31/2012: day 366 of 2012 (Leap Year)
//       12/31/2013: day 365 of 2013
//       12/31/2014: day 365 of 2014
//       12/31/2015: day 365 of 2015
//       12/31/2016: day 366 of 2016 (Leap Year)
//       12/31/2017: day 365 of 2017
//       12/31/2018: day 365 of 2018
//       12/31/2019: day 365 of 2019
//       12/31/2020: day 366 of 2020 (Leap Year)

Option Strict On

Module Example
Public Sub Main()
Dim dec31 As Date = #12/31/2010#
For ctr As Integer = 0 To 10
Dim dateToDisplay As Date = dec31.AddYears(ctr)
Console.WriteLine("{0:d}: day {1} of {2} {3}", dateToDisplay,
dateToDisplay.DayOfYear,
dateToDisplay.Year,
If(DateTime.IsLeapYear(dateToDisplay.Year),
"(Leap Year)", ""))

Next
End Sub
End Module
' The example displays the following output:
'       12/31/2010: day 365 of 2010
'       12/31/2011: day 365 of 2011
'       12/31/2012: day 366 of 2012 (Leap Year)
'       12/31/2013: day 365 of 2013
'       12/31/2014: day 365 of 2014
'       12/31/2015: day 365 of 2015
'       12/31/2016: day 366 of 2016 (Leap Year)
'       12/31/2017: day 365 of 2017
'       12/31/2018: day 365 of 2018
'       12/31/2019: day 365 of 2019
'       12/31/2020: day 366 of 2020 (Leap Year)


## 注釈

プロパティは DayOfYear 、年の日を計算するときにうるう年を考慮します。 プロパティの値は、現在のカルチャの現在のカレンダーに関係なく、グレゴリオ暦の年の日を常に反映します。 別のカレンダーで年の日を取得するには、そのカレンダーの メソッドを Calendar.GetDayOfYear 呼び出します。