DateTime

Object –> ValueType –> DateTime
Represents an instant in time.

Note: Time values are measured in 100-nanosecond units called ticks.
Note: System.DateOnly is useful if working with dates only. This type maps to date columns in SQL server.
Note: System.TimeOnly is useful if working with times only. This type maps to time columns in SQL server.

Also: https://docs.microsoft.com/en-us/dotnet/standard/base-types/standard-date-and-time-format-strings

Uses

Work with dates only or times only
Work with dates and times for which timezone information is missing
Work with UTC dates and times only
Retrieve date/time information from sources outside of .NET

Construction

DateTime(yyyy, mm, dd, hh, mm, ss) // hh, mm, ss are optional.
DateTime(yyyy, mm, dd, hh, mm, ss, ms) // ms is optional.
DateTime(ticks) // where ticks is an Int64.

Properties

Note: Properties contained within DateTimeOffset are not listed here.

.Kind // A value that specifies if this DateTime is based on local time, UTC, or neither.

Methods

Note: Methods contained within DateTimeOffset are not listed here.

Information

DateTime.DaysInMonth(mm, yyyy)
DateTime.IsLeapYear(year)

.GetDateTimeFormats()
.IsDaylightSavingsTime() // Boolean if this instance is within the daylight savings time range for the current timezone.

Converting

DateTime.FromBinary(int64)Convert a 64-bit binary value to DateTime.
DateTime.SpecifyKind(DateTime, DateTimeKind)

.ToLongDateString()
.ToLongTimeString()
.ToShortDateString()
.ToShortTimeString()
.ToString()
.ToUniversalTime()

Parsing

.Parse(string) // Parse string into a DateTime object.
.TryParse(string, out DateTime result) // Try to parse string into DateTime result.

Adding and Subtracting

.Add()
.AddDays()
.AddHours()
.AddMilliseconds()
.AddMinutes()
.AddMonths()
.AddTicks()
.AddYears()

Note: add negative numbers to subtract.

Format Specifiers

https://docs.microsoft.com/en-us/dotnet/api/system.datetime.tostring?view=net-6.0