How to Write a Program to Find a Leap Year in C# [2 Methods]

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Find a Leap Year in C#

A leap year, occurring every four years, has 366 days instead of the usual 365, thanks to an extra day in February. Do you want to check a leap year in C#? In this tutorial, I will explain two methods to find a leap year in C#. So, let us start with writing a program to find a leap year in C#.

To determine if a year is a leap year in C#, you can use a simple method that checks three conditions: if the year is divisible by 4, not divisible by 100, except when it’s also divisible by 400. The code snippet bool isLeapYear = (year % 4 == 0 && year % 100 != 0) || (year % 400 == 0); efficiently performs this check, returning true for a leap year and false otherwise. This concise approach ensures accurate leap year identification in C#.

Write a Program to Find a Leap Year in C#

First, let us understand the rules that define a leap year:

  1. A year is a leap year if it is divisible by 4.
  2. However, if the year is also divisible by 100, it is not a leap year.
  3. But, if it’s divisible by 400, it is a leap year.

Here is a complete program to check a leap year in C#.

using System;

class LeapYearProgram
{
    static void Main(string[] args)
    {
        Console.WriteLine("Enter a year to check if it's a leap year:");
        int year = Convert.ToInt32(Console.ReadLine());

        if (IsLeapYear(year))
        {
            Console.WriteLine($"{year} is a leap year.");
        }
        else
        {
            Console.WriteLine($"{year} is not a leap year.");
        }
    }

    static bool IsLeapYear(int year)
    {
        if ((year % 4 == 0 && year % 100 != 0) || (year % 400 == 0))
        {
            return true;
        }
        return false;
    }
}
  • Main Method: This is where the program starts. It prompts the user to enter a year and then calls the IsLeapYear method.
  • IsLeapYear Method: This method encapsulates the leap year logic. It returns true if the year is a leap year and false otherwise.

Once you run the code, it will ask you to enter a year to check if it is a leap year or not. Then, it will check and show the output, like in the screenshot below. I inserted 2024, and it is showing me it is a leap year.

Find a Leap Year in C#

Find a Leap Year in C# using DateTime.IsLeapYear Method

C# provides a built-in method in the System namespace to check if a year is a leap year. This method abstracts away the underlying calculations and provides a direct way to determine leap years. So, here is another program to check if a year is a leap year in C# using the DateTime.IsLeapYear() method.

In this approach, you simply pass the year to the DateTime.IsLeapYear method, and it returns true if the year is a leap year or false otherwise.

using System;

class LeapYearChecker
{
    static void Main()
    {
        Console.WriteLine("Enter a year to check if it's a leap year:");
        int year = Convert.ToInt32(Console.ReadLine());

        if (DateTime.IsLeapYear(year))
        {
            Console.WriteLine($"{year} is a leap year.");
        }
        else
        {
            Console.WriteLine($"{year} is not a leap year.");
        }
    }
}

Here, you can see the output in the screenshot below. I entered 2024 as a year, and it is showing 2024 as a leap year.

Write A Program To Find A Leap Year In C#

In the next screenshot below, you can see I entered 2025, and it shows me 2025 is not a leap year after I executed the above C# program.

How to Write a Program to Find a Leap Year in C#

Conclusion

The built-in DateTime.IsLeapYear() method is the most straightforward and reliable approach provided by the .NET framework to find a leap year in C#. I hope you got to know how to write a program to find a leap year in C#. We have explained here 2 different methods to check a leap year in C#. A lot of time, you will find this is C# Interview Questions for 5 Years Experience.

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