DKNet
Find calendar quarters and month ends
Part of DKNet.Fw.Extensions. Use DateTimeExtensions for calendar quarter numbers and the last day of the same month.
using System;
using DKNet.Fw.Extensions.Primitives;
var date = new DateTime(2026, 2, 10, 12, 30, 0, DateTimeKind.Utc);
Console.WriteLine(date.InQuarter()); // 1
Console.WriteLine(date.LastDayOfMonth().ToString("O")); // 2026-02-28T12:30:00.0000000Z
Console.WriteLine(((DateTime?)null).LastDayOfMonth() is null); // True
InQuarter() computes ((Month - 1) / 3) + 1. LastDayOfMonth() uses DateTime.AddDays, preserving the original time, subsecond precision and Kind. Its nullable overload returns null for null input.
⚠️ Gotchas & limits
- Month end is not midnight unless the input time was midnight.
- These are calendar operations on
DateTime; there is no time-zone conversion or fiscal-calendar setting.