今日は土曜日と日曜日だけでなく休日も除外する方法を見つける必要があったため、この投稿を復活させます。具体的には、次のようなさまざまな休日を処理する必要がありました。
- 国に依存しない休日（少なくとも西側諸国では-01、01など）。
- 計算された休日（イースターやイースター月曜日など）。
- 国固有の休日（イタリア解放日や米国ID4など）。
- 町固有の休日（ローマ聖パトロンの日など）。
- その他のカスタムメイドの休日（「明日のオフィスは閉鎖されます」など）。
結局、私は次のヘルパー/拡張機能クラスのセットを思い付きました。それらは明らかにエレガントではありませんが、非効率的なループを大量に使用するため、問題を完全に解決するには十分です。この投稿では、ソースコード全体を削除します。他の人にも役立つことを願っています。
ソースコード
/// <summary>
/// Helper/extension class for manipulating date and time values.
/// </summary>
public static class DateTimeExtensions
{
/// <summary>
/// Calculates the absolute year difference between two dates.
/// </summary>
/// <param name="dt1"></param>
/// <param name="dt2"></param>
/// <returns>A whole number representing the number of full years between the specified dates.</returns>
public static int Years(DateTime dt1,DateTime dt2)
{
return Months(dt1,dt2)/12;
//if (dt2<dt1)
//{
// DateTime dt0=dt1;
// dt1=dt2;
// dt2=dt0;
//}
//int diff=dt2.Year-dt1.Year;
//int m1=dt1.Month;
//int m2=dt2.Month;
//if (m2>m1) return diff;
//if (m2==m1 && dt2.Day>=dt1.Day) return diff;
//return (diff-1);
}
/// <summary>
/// Calculates the absolute year difference between two dates.
/// Alternative, stand-alone version (without other DateTimeUtil dependency nesting required)
/// </summary>
/// <param name="start"></param>
/// <param name="end"></param>
/// <returns></returns>
public static int Years2(DateTime start, DateTime end)
{
return (end.Year - start.Year - 1) +
(((end.Month > start.Month) ||
((end.Month == start.Month) && (end.Day >= start.Day))) ? 1 : 0);
}
/// <summary>
/// Calculates the absolute month difference between two dates.
/// </summary>
/// <param name="dt1"></param>
/// <param name="dt2"></param>
/// <returns>A whole number representing the number of full months between the specified dates.</returns>
public static int Months(DateTime dt1,DateTime dt2)
{
if (dt2<dt1)
{
DateTime dt0=dt1;
dt1=dt2;
dt2=dt0;
}
dt2=dt2.AddDays(-(dt1.Day-1));
return (dt2.Year-dt1.Year)*12+(dt2.Month-dt1.Month);
}
/// <summary>
/// Returns the higher of the two date time values.
/// </summary>
/// <param name="dt1">The first of the two <c>DateTime</c> values to compare.</param>
/// <param name="dt2">The second of the two <c>DateTime</c> values to compare.</param>
/// <returns><c>dt1</c> or <c>dt2</c>, whichever is higher.</returns>
public static DateTime Max(DateTime dt1,DateTime dt2)
{
return (dt2>dt1?dt2:dt1);
}
/// <summary>
/// Returns the lower of the two date time values.
/// </summary>
/// <param name="dt1">The first of the two <c>DateTime</c> values to compare.</param>
/// <param name="dt2">The second of the two <c>DateTime</c> values to compare.</param>
/// <returns><c>dt1</c> or <c>dt2</c>, whichever is lower.</returns>
public static DateTime Min(DateTime dt1,DateTime dt2)
{
return (dt2<dt1?dt2:dt1);
}
/// <summary>
/// Adds the given number of business days to the <see cref="DateTime"/>.
/// </summary>
/// <param name="current">The date to be changed.</param>
/// <param name="days">Number of business days to be added.</param>
/// <param name="holidays">An optional list of holiday (non-business) days to consider.</param>
/// <returns>A <see cref="DateTime"/> increased by a given number of business days.</returns>
public static DateTime AddBusinessDays(
this DateTime current,
int days,
IEnumerable<DateTime> holidays = null)
{
var sign = Math.Sign(days);
var unsignedDays = Math.Abs(days);
for (var i = 0; i < unsignedDays; i++)
{
do
{
current = current.AddDays(sign);
}
while (current.DayOfWeek == DayOfWeek.Saturday
|| current.DayOfWeek == DayOfWeek.Sunday
|| (holidays != null && holidays.Contains(current.Date))
);
}
return current;
}
/// <summary>
/// Subtracts the given number of business days to the <see cref="DateTime"/>.
/// </summary>
/// <param name="current">The date to be changed.</param>
/// <param name="days">Number of business days to be subtracted.</param>
/// <param name="holidays">An optional list of holiday (non-business) days to consider.</param>
/// <returns>A <see cref="DateTime"/> increased by a given number of business days.</returns>
public static DateTime SubtractBusinessDays(
this DateTime current,
int days,
IEnumerable<DateTime> holidays)
{
return AddBusinessDays(current, -days, holidays);
}
/// <summary>
/// Retrieves the number of business days from two dates
/// </summary>
/// <param name="startDate">The inclusive start date</param>
/// <param name="endDate">The inclusive end date</param>
/// <param name="holidays">An optional list of holiday (non-business) days to consider.</param>
/// <returns></returns>
public static int GetBusinessDays(
this DateTime startDate,
DateTime endDate,
IEnumerable<DateTime> holidays)
{
if (startDate > endDate)
throw new NotSupportedException("ERROR: [startDate] cannot be greater than [endDate].");
int cnt = 0;
for (var current = startDate; current < endDate; current = current.AddDays(1))
{
if (current.DayOfWeek == DayOfWeek.Saturday
|| current.DayOfWeek == DayOfWeek.Sunday
|| (holidays != null && holidays.Contains(current.Date))
)
{
// skip holiday
}
else cnt++;
}
return cnt;
}
/// <summary>
/// Calculate Easter Sunday for any given year.
/// src.: https://stackoverflow.com/a/2510411/1233379
/// </summary>
/// <param name="year">The year to calcolate Easter against.</param>
/// <returns>a DateTime object containing the Easter month and day for the given year</returns>
public static DateTime GetEasterSunday(int year)
{
int day = 0;
int month = 0;
int g = year % 19;
int c = year / 100;
int h = (c - (int)(c / 4) - (int)((8 * c + 13) / 25) + 19 * g + 15) % 30;
int i = h - (int)(h / 28) * (1 - (int)(h / 28) * (int)(29 / (h + 1)) * (int)((21 - g) / 11));
day = i - ((year + (int)(year / 4) + i + 2 - c + (int)(c / 4)) % 7) + 28;
month = 3;
if (day > 31)
{
month++;
day -= 31;
}
return new DateTime(year, month, day);
}
/// <summary>
/// Retrieve holidays for given years
/// </summary>
/// <param name="years">an array of years to retrieve the holidays</param>
/// <param name="countryCode">a country two letter ISO (ex.: "IT") to add the holidays specific for that country</param>
/// <param name="cityName">a city name to add the holidays specific for that city</param>
/// <returns></returns>
public static IEnumerable<DateTime> GetHolidays(IEnumerable<int> years, string countryCode = null, string cityName = null)
{
var lst = new List<DateTime>();
foreach (var year in years.Distinct())
{
lst.AddRange(new[] {
new DateTime(year, 1, 1), // 1 gennaio (capodanno)
new DateTime(year, 1, 6), // 6 gennaio (epifania)
new DateTime(year, 5, 1), // 1 maggio (lavoro)
new DateTime(year, 8, 15), // 15 agosto (ferragosto)
new DateTime(year, 11, 1), // 1 novembre (ognissanti)
new DateTime(year, 12, 8), // 8 dicembre (immacolata concezione)
new DateTime(year, 12, 25), // 25 dicembre (natale)
new DateTime(year, 12, 26) // 26 dicembre (s. stefano)
});
// add easter sunday (pasqua) and monday (pasquetta)
var easterDate = GetEasterSunday(year);
lst.Add(easterDate);
lst.Add(easterDate.AddDays(1));
// country-specific holidays
if (!String.IsNullOrEmpty(countryCode))
{
switch (countryCode.ToUpper())
{
case "IT":
lst.Add(new DateTime(year, 4, 25)); // 25 aprile (liberazione)
break;
case "US":
lst.Add(new DateTime(year, 7, 4)); // 4 luglio (Independence Day)
break;
// todo: add other countries
case default:
// unsupported country: do nothing
break;
}
}
// city-specific holidays
if (!String.IsNullOrEmpty(cityName))
{
switch (cityName)
{
case "Rome":
case "Roma":
lst.Add(new DateTime(year, 6, 29)); // 29 giugno (s. pietro e paolo)
break;
case "Milano":
case "Milan":
lst.Add(new DateTime(year, 12, 7)); // 7 dicembre (s. ambrogio)
break;
// todo: add other cities
default:
// unsupported city: do nothing
break;
}
}
}
return lst;
}
}
使用情報
コードは一目瞭然ですが、使用方法を説明するいくつかの例を以下に示します。
追加の10営業日（土曜日と日曜日の平日のみをスキップ）
var dtResult = DateTimeUtil.AddBusinessDays(srcDate, 10);
10営業日追加します（2019年の土曜日、日曜日、および国に依存しないすべての休日をスキップします）
var dtResult = DateTimeUtil.AddBusinessDays(srcDate, 10, GetHolidays(2019));
10営業日を追加します（土、日、2019年のすべてのイタリアの休日をスキップします）
var dtResult = DateTimeUtil.AddBusinessDays(srcDate, 10, GetHolidays(2019, "IT"));
10営業日を追加します（土曜日、日曜日、イタリアのすべての休日、2019年のローマ固有の休日をスキップします）
var dtResult = DateTimeUtil.AddBusinessDays(srcDate, 10, GetHolidays(2019, "IT", "Rome"));
上記の関数とコード例は、私のブログのこの投稿でさらに説明されています。