DateTime

Struct · namespace System · Since 0.19

struct DateTime : IComparable<DateTime>, IEquatable<DateTime>, IHashable

A date and time of day, local or UTC.

var now = DateTime.Now();
Console.WriteLine(now.ToString("yyyy-MM-dd HH:mm"));
var deadline = now.AddDays(3);
TimeSpan left = deadline.Subtract(now);           // 3.00:00:00

A DateTime counts ticks of 100 ns from 0001-01-01 to 9999-12-31 (the Gregorian calendar), either in local time or in UTC (DateTime.IsUtc); DateTime.Now is local, DateTime.UtcNow UTC. The clock and the time zone come from the operating system. Like the .NET type, with methods instead of properties.

Fields

Name	Description
`Ticks`	The ticks of 100 ns since 0001-01-01 00:00.
`IsUtc`	Whether the time is UTC (otherwise it is local time).

Ticks

int64 Ticks

The ticks of 100 ns since 0001-01-01 00:00.

IsUtc

bool IsUtc

Whether the time is UTC (otherwise it is local time).

Static methods

Name	Description
`UtcNow`	The current date and time in UTC.
`Now`	The current date and time in local time.
`Today`	today’s date (local) at 00:00
`Create`	A local date at 00:00.
`CreateUtc`	A date and time in UTC.
`FromUnixSeconds`	The UTC date and time `seconds` seconds after 1970-01-01 00:00 UTC (Unix time).
`FromUnixMilliseconds`	The UTC date and time `milliseconds` milliseconds after 1970-01-01 00:00 UTC.
`IsLeapYear`	Whether `year` is a leap year in the Gregorian calendar.
`DaysInMonth`	The number of days of `month` (1 to 12) in `year`.
`Parse`	Reads a date and time: `yyyy-MM-dd`, optionally followed by `T` or a space and `HH:mm[:ss[.fffffff]]`, then `Z` (UTC) or `+hh:mm` / `-hh:mm` (UTC, converted from that offset).

UtcNow

static DateTime UtcNow()

The current date and time in UTC.

Now

static DateTime Now()

The current date and time in local time.

Today

static DateTime Today()

today’s date (local) at 00:00

Create

static DateTime Create(int year, int month, int day)

A local date at 00:00.

Panics when the date does not exist.

static DateTime Create(int year, int month, int day, int hour, int minute, int second)

A local date and time.

Panics when the date or time does not exist.

static DateTime Create(int year, int month, int day, int hour, int minute, int second, int millisecond)

A local date and time with milliseconds.

Panics when the date or time does not exist.

CreateUtc

static DateTime CreateUtc(int year, int month, int day, int hour, int minute, int second)

A date and time in UTC.

Panics when the date or time does not exist.

FromUnixSeconds

static DateTime FromUnixSeconds(int64 seconds)

The UTC date and time seconds seconds after 1970-01-01 00:00 UTC (Unix time).

FromUnixMilliseconds

static DateTime FromUnixMilliseconds(int64 milliseconds)

The UTC date and time milliseconds milliseconds after 1970-01-01 00:00 UTC.

IsLeapYear

static bool IsLeapYear(int year)

Whether year is a leap year in the Gregorian calendar.

DaysInMonth

static int DaysInMonth(int year, int month)

The number of days of month (1 to 12) in year.

Parse

static ParseError<DateTime> Parse(string text)

Reads a date and time: yyyy-MM-dd, optionally followed by T or a space and HH:mm[:ss[.fffffff]], then Z (UTC) or +hh:mm / -hh:mm (UTC, converted from that offset). Without a zone the time is local.

Errors

ParseError.Invalid: the text has another format.
ParseError.OutOfRange: the date or time does not exist.

Methods

Name	Description
`ToUnixSeconds`	The seconds since 1970-01-01 00:00 UTC (Unix time); a local time is converted to UTC first.
`ToUnixMilliseconds`	The milliseconds since 1970-01-01 00:00 UTC; a local time is converted to UTC first.
`Year`	The year (1 to 9999).
`Month`	The month (1 to 12).
`Day`	The day of the month (1 to 31).
`Hour`	The hour (0 to 23).
`Minute`	The minute (0 to 59).
`Second`	The second (0 to 59).
`Millisecond`	The millisecond (0 to 999).
`DayOfWeek`	The day of the week.
`DayOfYear`	The day of the year (1 to 366).
`Date`	The date at 00:00 (the same zone).
`TimeOfDay`	The time since 00:00.
`Add`	The date and time `span` later (earlier for a negative span).
`AddTicks`	The date and time `ticks` ticks of 100 ns later.
`AddDays`	The date and time `days` days later (fractions are possible).
`AddHours`	The date and time `hours` hours later.
`AddMinutes`	The date and time `minutes` minutes later.
`AddSeconds`	The date and time `seconds` seconds later.
`AddMilliseconds`	The date and time `milliseconds` milliseconds later.
`AddMonths`	The date `months` whole months later: the day stays, or becomes the last day of a shorter month (Jan 31 + 1 month is Feb 28 or 29).
`AddYears`	The date `years` years later (Feb 29 becomes Feb 28 in a year that is not a leap year).
`Subtract`	The time from `other` to this date (both are taken in UTC if one of them is).
`ToUniversalTime`	The same instant in UTC (a UTC value stays as it is).
`ToLocalTime`	The same instant in local time (a local value stays as it is).
`CompareTo`	compares the instants (a local and a UTC value are compared in UTC)
`Equals`	Whether both are the same instant and zone (`IEquatable`).
`GetHashCode`	A hash code of the date and time (`IHashable`).
`ToString`	The date and time as text: `2026-10-01 14:05:09`.
`ToIsoString`	ISO 8601 with the zone: 2026-10-01T12:05:09.250Z (UTC) or 2026-10-01T14:05:09.250+02:00 (local)

ToUnixSeconds

int64 ToUnixSeconds()

The seconds since 1970-01-01 00:00 UTC (Unix time); a local time is converted to UTC first.

ToUnixMilliseconds

int64 ToUnixMilliseconds()

The milliseconds since 1970-01-01 00:00 UTC; a local time is converted to UTC first.

Year

int Year()

The year (1 to 9999).

Month

int Month()

The month (1 to 12).

Day

int Day()

The day of the month (1 to 31).

Hour

int Hour()

The hour (0 to 23).

Minute

int Minute()

The minute (0 to 59).

Second

int Second()

The second (0 to 59).

Millisecond

int Millisecond()

The millisecond (0 to 999).

DayOfWeek

DayOfWeek DayOfWeek()

The day of the week.

DayOfYear

int DayOfYear()

The day of the year (1 to 366).

Date

DateTime Date()

The date at 00:00 (the same zone).

TimeOfDay

TimeSpan TimeOfDay()

The time since 00:00.

Add

DateTime Add(TimeSpan span)

The date and time span later (earlier for a negative span).

AddTicks

DateTime AddTicks(int64 ticks)

The date and time ticks ticks of 100 ns later.

AddDays

DateTime AddDays(double days)

The date and time days days later (fractions are possible).

AddHours

DateTime AddHours(double hours)

The date and time hours hours later.

AddMinutes

DateTime AddMinutes(double minutes)

The date and time minutes minutes later.

AddSeconds

DateTime AddSeconds(double seconds)

The date and time seconds seconds later.

AddMilliseconds

DateTime AddMilliseconds(double milliseconds)

The date and time milliseconds milliseconds later.

AddMonths

DateTime AddMonths(int months)

The date months whole months later: the day stays, or becomes the last day of a shorter month (Jan 31 + 1 month is Feb 28 or 29).

AddYears

DateTime AddYears(int years)

The date years years later (Feb 29 becomes Feb 28 in a year that is not a leap year).

Subtract

TimeSpan Subtract(DateTime other)

The time from other to this date (both are taken in UTC if one of them is).

DateTime Subtract(TimeSpan span)

The date and time span earlier.

ToUniversalTime

DateTime ToUniversalTime()

The same instant in UTC (a UTC value stays as it is). Near a change of daylight saving time, the offset of the result decides.

ToLocalTime

DateTime ToLocalTime()

The same instant in local time (a local value stays as it is).

CompareTo

int CompareTo(DateTime other)

compares the instants (a local and a UTC value are compared in UTC)

Equals

bool Equals(DateTime other)

Whether both are the same instant and zone (IEquatable).

GetHashCode

int GetHashCode()

A hash code of the date and time (IHashable).

ToString

string ToString()

The date and time as text: 2026-10-01 14:05:09.

string ToString(string format)

The date and time in a custom format: d.ToString("dd.MM.yyyy HH:mm").

Letters	Meaning
`yyyy` `yy`	the year with 4 or 2 digits
`MMMM` `MMM` `MM` `M`	the month: its name, the short name, 2 digits, the number
`dddd` `ddd` `dd` `d`	the day: the name of the weekday, its short name, 2 digits, the number
`HH` `H`	the hour, 0 to 23 (2 digits or the number)
`hh` `h`	the hour, 1 to 12
`mm` `m`	the minute
`ss` `s`	the second
`fff` `ff` `f`	fractions of a second
`tt`	`AM` or `PM`

Other letters and text in '...' are copied; \x copies x. The names are English.

ToIsoString

string ToIsoString()

ISO 8601 with the zone: 2026-10-01T12:05:09.250Z (UTC) or 2026-10-01T14:05:09.250+02:00 (local)