Working with Date and Time in C#

C# includes DateTime struct to work with dates and times.

To work with date and time in C#, create an object of the DateTime struct using the new keyword. The following creates a DateTime object with the default value.

DateTime dt = new DateTime(); // assigns default value 01/01/0001 00:00:00

The default and the lowest value of a DateTime object is January 1, 0001 00:00:00 (midnight). The maximum value can be December 31, 9999 11:59:59 P.M.

Use different constructors of the DateTime struct to assign an initial value to a DateTime object.

//assigns default value 01/01/0001 00:00:00
DateTime dt1 = new DateTime(); 

//assigns year, month, day
DateTime dt2 = new DateTime(2015, 12, 31); 

//assigns year, month, day, hour, min, seconds
DateTime dt3 = new DateTime(2015, 12, 31, 5, 10, 20);
 
//assigns year, month, day, hour, min, seconds, UTC timezone
DateTime dt4 = new DateTime(2015, 12, 31, 5, 10, 20, DateTimeKind.Utc);

In the above example, we specified a year, a month, and a day in the constructor. The year can be from 0001 to 9999, and the Month can be from 1 to 12, and the day can be from 1 to 31. Setting any other value out of these ranges will result in a run-time exception.

DateTime dt = new DateTime(2015, 12, 32); //throws exception: day out of range

Use different DateTime constructors to set date, time, time zone, calendar, and culture.

Ticks

Ticks is a date and time expressed in the number of 100-nanosecond intervals that have elapsed since January 1, 0001, at 00:00:00.000 in the Gregorian calendar. The following initializes a DateTime object with the number of ticks.

DateTime dt = new DateTime(636370000000000000); 
DateTime.MinValue.Ticks;  //min value of ticks
DateTime.MaxValue.Ticks; // max value of ticks

DateTime Static Fields

The DateTime struct includes static fields, properties, and methods. The following example demonstrates important static fields and properties.

DateTime currentDateTime = DateTime.Now;  //returns current date and time
DateTime todaysDate = DateTime.Today; // returns today's date
DateTime currentDateTimeUTC = DateTime.UtcNow;// returns current UTC date and time

DateTime maxDateTimeValue = DateTime.MaxValue; // returns max value of DateTime
DateTime minDateTimeValue = DateTime.MinValue; // returns min value of DateTime

TimeSpan

TimeSpan is a struct that is used to represent time in days, hour, minutes, seconds, and milliseconds.

DateTime dt = new DateTime(2015, 12, 31);
           
TimeSpan ts = new TimeSpan(25,20,55);
 
DateTime newDate = dt.Add(ts);

Console.WriteLine(newDate);//1/1/2016 1:20:55 AM

Subtraction of two dates results in TimeSpan.

DateTime dt1 = new DateTime(2015, 12, 31); 
DateTime dt2 = new DateTime(2016, 2, 2);
TimeSpan result = dt2.Subtract(dt1);//33.00:00:00

Operators

The DateTime struct overloads +, -, ==, !=, >, <, <=, >= operators to ease out addition, subtraction, and comparison of dates. These make it easy to work with dates.

DateTime dt1 = new DateTime(2015, 12, 20);
DateTime dt2 = new DateTime(2016, 12, 31, 5, 10, 20); 
TimeSpan time = new TimeSpan(10, 5, 25, 50);

Console.WriteLine(dt2 + time); // 1/10/2017 10:36:10 AM
Console.WriteLine(dt2 - dt1); //377.05:10:20
Console.WriteLine(dt1 == dt2); //False
Console.WriteLine(dt1 != dt2); //True
Console.WriteLine(dt1 > dt2); //False
Console.WriteLine(dt1 < dt2); //True
Console.WriteLine(dt1 >= dt2); //False
Console.WriteLine(dt1 <= dt2);//True

Convert String to DateTime

A valid date and time string can be converted to a DateTime object using Parse(), ParseExact(), TryParse() and TryParseExact() methods.

The Parse() and ParseExact() methods will throw an exception if the specified string is not a valid representation of a date and time. So, it's recommended to use TryParse() or TryParseExact() method because they return false if a string is not valid.

var str = "5/12/2020";
DateTime dt;
            
var isValidDate = DateTime.TryParse(str, out dt);

if(isValidDate)
    Console.WriteLine(dt);
else
    Console.WriteLine($"{str} is not a valid date string");