Calcul des jours fériés et des jours ouvrés par mois et année en France.
https://dotnetfiddle.net/ql8sZW
var today = DateTime.Today;
Console.WriteLine($"Nous sommes le {today}.");
var isDayOff = new WorkingDaysCalculator(new FrenchPublicHolidaysCalculator()).IsDayOff(today);
var dayOffLabel = isDayOff ? "non " : "";
Console.WriteLine($"Le {today.ToLongDateString()} est un jour {dayOffLabel}travaillé en France.");
var nbWorkingDays = new WorkingDaysCalculator(new FrenchPublicHolidaysCalculator()).GetWorkingDaysByMonth(today.Year, today.Month);
Console.WriteLine($"Il y a {nbWorkingDays} jour(s) travaillé(s) en {today.ToString("MMMM")} {today.Year}.");
var result = new FrenchPublicHolidaysCalculator().GetPublicHolidays(today.Year);
Console.WriteLine($"Il y a {result.Count()} jours fériés en France en {today.Year} :");
foreach (var item in result)
{
Console.WriteLine(item.ToString("D"));
}