DateTime.AddMilliseconds() Method in C#

This method is used to return a new DateTime that adds the specified number of milliseconds to the value of this instance. 

Syntax:

public DateTime AddMilliseconds (double value);

Here, it takes a number of whole and fractional milliseconds. The value parameter can be negative or positive and is rounded to the nearest integer. 

Return Value: This method returns an object whose value is the sum of the date and time represented by this instance and the number of milliseconds represented by value. 

Exceptions: This method will give ArgumentOutOfRangeException if the resulting DateTime is less than MinValue or greater than MaxValue.

Below programs illustrate the use of DateTime.AddMilliseconds(Double) Method: 

Example 1:

csharp

// C# program to demonstrate the
// DateTime.AddMilliseconds() Method
using System;

class GFG {

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

            // creating object of DateTime
            DateTime date1 = new DateTime(2010, 1, 1,
                                           4, 0, 15);

            // adding the 3000 Milliseconds
            // using AddMilliseconds() method;
            DateTime date2 = date1.AddMilliseconds(3000);

            // Display the date1
            Console.WriteLine("DateTime before operation: "
                           + "{0:hh}:{0:mm}:{0:ss}", date1);


            // Display the date2
            Console.WriteLine("\nDateTime after operation: "
                           + "{0:hh}:{0:mm}:{0:ss}", date2);

        }

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

Output:

DateTime before operation: 04:00:15

DateTime after operation: 04:00:18

Example 2: For ArgumentOutOfRangeException 

csharp

// C# program to demonstrate the
// DateTime.AddMilliseconds() Method
using System;

class GFG {

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

            // creating object of DateTime
            // and initialize with MinValue
            DateTime date1 = DateTime.MaxValue;

            // Display the date1
            Console.WriteLine("DateTime before operation: "
                                         + "{0}", date1);


            // adding the 3000 Milliseconds
            // using AddMilliseconds() method;
            DateTime date2 = date1.AddMilliseconds(3000);

            // Display the date2
            Console.WriteLine("\nDateTime after operation: "
                           + "{0:hh}:{0:mm}:{0:ss}", date2);

        }

        catch (ArgumentOutOfRangeException e)
        {
            Console.WriteLine("\nThe resulting DateTime is "+
                      "greater than the DateTime.MaxValue ");

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

Output:

DateTime before operation: 12/31/9999 23:59:59

The resulting DateTime is greater than the DateTime.MaxValue 
Exception Thrown: System.ArgumentOutOfRangeException

Reference:

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