DateTimeOffset.Add() Method in C#

This method is used to return a new DateTimeOffset object that adds a specified time interval to the value of this instance.

Syntax: public DateTimeOffset Add (TimeSpan timeSpan); 
Here, it takes a TimeSpan object that represents a positive or a negative time interval.
Return Value: This method returns an object whose value is the sum of the date and time represented by the current DateTimeOffset object and the time interval represented by timeSpan.
Exception: This method will give ArgumentOutOfRangeException if The resulting DateTimeOffset value is less than MinValue or the resulting DateTimeOffset value is greater than MaxValue. 

Below programs illustrate the use of DateTimeOffset.Add(TimeSpan) Method:
Example 1:

csharp

// C# program to demonstrate the
// DateTimeOffset.Add(TimeSpan)
// Method
using System;
using System.Globalization;

class GFG {

    // Main Method
    public static void Main()
    {
        try {

            // creating object of  DateTimeOffset
            DateTimeOffset offset = new DateTimeOffset(2007,
                    6, 1, 7, 55, 0, new TimeSpan(-5, 0, 0));


            // creating object of TimeSpan
            TimeSpan elapsedTime = new TimeSpan(10, 0, 0);

            // adding a specified time interval
            // to the value of this instance.
            // using Add() method;
            DateTimeOffset value = offset.Add(elapsedTime);

            // Display the time
            Console.WriteLine("DateTimeOffset is {0}", value);
        }

        catch (ArgumentOutOfRangeException e)
        {
            Console.Write("Exception Thrown: ");
            Console.Write("{0}", e.GetType(), e.Message);
        }
    }
}

Output:

DateTimeOffset is 06/01/2007 17:55:00 -05:00

Example 2: For ArgumentOutOfRangeException

csharp

// C# program to demonstrate the
// DateTimeOffset.Add(TimeSpan)
// Method
using System;
using System.Globalization;

class GFG {

    // Main Method
    public static void Main()
    {
        try {

            // creating object of  DateTimeOffset
            DateTimeOffset offset = DateTimeOffset.MaxValue;

            // creating object of TimeSpan
            TimeSpan elapsedTime = new TimeSpan(10, 0, 0);

            // adding a specified time interval
            // to the value of this instance.
            // using Add() method;
            DateTimeOffset value = offset.Add(elapsedTime);

            // Display the time
            Console.WriteLine("DateTimeOffset is {0}", value);
        }

        catch (ArgumentOutOfRangeException e)
        {
            Console.Write("Exception Thrown: ");
            Console.Write("{0}", e.GetType(), e.Message);
        }
    }
}

Output:

Exception Thrown: System.ArgumentOutOfRangeException

Reference:

• https://docs.microsoft.com/en-us/dotnet/api/system.datetimeoffset.add?view=netframework-4.7.2