How to Get First and Last Day of the Year in C#?

Do you want to get the first or last day of the year in C#? In this C# tutorial, I will explain to you how to get the first and last day of the year in C#.

I will also show you how to calculate the first and last day of the current year and display their day names (like “Sunday” or “Monday”).

Table of Contents

Get the First Day of the Year in C#

The first day of any year is simply January 1st of that year. In C#, you can get the first day of the current year by using the DateTime structure. Here’s how you can do it:

int currentYear = DateTime.Now.Year; // This gets the current year
DateTime firstDayOfYear = new DateTime(currentYear, 1, 1); // January 1st of the current year

This code uses DateTime.Now.Year to find out the current year and then creates a new DateTime object representing January 1st of that year.

Get Last Day of the Year in C#

The last day of any year is December 31st of that year. Similar to getting the first day, you can get the last day of the year like this:

int currentYear = DateTime.Now.Year; // This gets the current year
DateTime lastDayOfYear = new DateTime(currentYear, 12, 31); // December 31st of the current year

Here, we again use DateTime.Now.Year to get the current year and then instantiate a new DateTime object for December 31st of the current year.

Practical Usage

Knowing how to get the first and last day of the year can be useful in many scenarios, such as generating reports for the year, calculating annual fees, or setting up schedules and reminders for year-end activities.

Formatting the Dates

Often, you’ll want to display these dates in a more readable format. C# provides powerful formatting options for DateTime objects. For example:

string formattedFirstDay = firstDayOfYear.ToString("MMMM dd, yyyy"); // "January 01, 2023"
string formattedLastDay = lastDayOfYear.ToString("MMMM dd, yyyy"); // "December 31, 2023"

The ToString method with a format string allows you to convert DateTime objects into a readable string format. The format string “MMMM dd, yyyy” will display the month in full, the day with a leading zero if necessary, and the full year.

First and Last Day of the Year in C# – Complete Code

Below is a simple C# console application that demonstrates how to obtain the first and last day of the current year. This code can be compiled and run in any C# development environment, such as Visual Studio or Visual Studio Code.

using System;

namespace DateTimeExample
{
    class Program
    {
        static void Main(string[] args)
        {
            // Get the current year
            int currentYear = DateTime.Now.Year;

            // Get the first day of the year
            DateTime firstDayOfYear = new DateTime(currentYear, 1, 1);

            // Get the last day of the year
            DateTime lastDayOfYear = new DateTime(currentYear, 12, 31);

            // Print the first day of the year
            Console.WriteLine("The first day of the year is: " + firstDayOfYear.ToString("MMMM dd, yyyy"));

            // Print the last day of the year
            Console.WriteLine("The last day of the year is: " + lastDayOfYear.ToString("MMMM dd, yyyy"));

            // Keep the console window open
            Console.WriteLine("Press any key to exit.");
            Console.ReadKey();
        }
    }
}

When you run this program, it will output something like this:

The first day of the year is: January 01, 2024
The last day of the year is: December 31, 2024
Press any key to exit.

The ToString method is used to format the dates in a human-readable form, specifically “Month Day, Year” format. The Console.ReadKey() at the end is used to prevent the console window from closing immediately after the program runs, allowing you to see the output before exiting.

You can see the screenshot below:

How to Get First and Last Day of the Year in Csharp

Get First and Last Day of the Year in C# (Like Sun day or Mon day)

To create a complete C# program that calculates the first and last day of the current year and displays their day names (like “Sunday” or “Monday”), you’ll need to use the DateTime class available in the .NET Framework. The program will:

Determine the current year.
Find the first day of the year (January 1st) and the last day of the year (December 31st).
Display the day names for both dates.

Here, you can see the complete program that you can execute using Visual Studio.

using System;

class Program
{
    static void Main()
    {
        // Get the current year
        int currentYear = DateTime.Now.Year;

        // First day of the year
        DateTime firstDay = new DateTime(currentYear, 1, 1);
        string firstDayName = firstDay.DayOfWeek.ToString();

        // Last day of the year
        DateTime lastDay = new DateTime(currentYear, 12, 31);
        string lastDayName = lastDay.DayOfWeek.ToString();

        // Output the results
        Console.WriteLine("First Day of the Year: " + firstDayName);
        Console.WriteLine("Last Day of the Year: " + lastDayName);
    }
}

Once you run the code, you can see the output in the screenshot below:

Get First and Last Day of the Year in C#

Conclusion

With the DateTime structure in C#, finding the first and last day of the current year is straightforward. In this C# tutorial, I have explained how to find the first and last day of the current year in C#.