Check Armstrong Number in Different Ways Using C#

In this article, I will discuss how to check Armstrong numbers in different ways using C#. This detailed article will cover the following topics,

1. What is an Armstrong Number?
2. Check Armstrong Number in Different Ways Using C#
3. Program to find Armstrong numbers between a range of numbers
4. Conclusion

What is an Armstrong Number?

As per Wikipedia, "A narcissistic number (also known as a pluperfect digital invariant (PPDI), an Armstrong number (after Michael F. Armstrong) or a plus perfect number) in a given number base b is a number that is the sum of its own digits each raised to the power of the number of digits".

In simple words, "An Armstrong number (also known as a narcissistic number) is a number that is equal to the sum of its own digits each raised to the power of the number of digits".

Example

Input: 153 -> Armstrong Number

Explanation: 153 = (1*1*1)+(5*5*5)+(3*3*3)

Where

• (1*1*1) = 1
• (5*5*5) = 125
• (3*3*3) = 27

So, 1 + 125 + 27 = 153

Check Armstrong Number in Different Ways Using C#

There are many ways to check if a number is an Armstrong number in C#. Below are some ways:

Method 1. Using While loop (with temporary variable)

This method iterates through each digit of the number, raising each to the power of the number of digits and adding the results. Let's see.

internal class ArmstrongNumberInCSharp
{
    static void Main(string[] args)
    {

        Console.Write("Enter the number: ");
        int number = int.Parse(Console.ReadLine());

        int result = 0, remainder = 0;
        int temporaryNumber = number;
        int count = number.ToString().Length;

        while (number > 0)
        {
            remainder = number % 10;
            result += (int)Math.Pow(remainder, count);
            number = number / 10;
        }

        if (result == temporaryNumber)
        {
            Console.WriteLine($"Yesss, {temporaryNumber} is an Armstrong Number!!");
        }
        else
        {
            Console.WriteLine($"Oohhh, {temporaryNumber} is not an Armstrong Number!!");
        }
        Console.ReadLine();
    }
}

Output

Method 2. Using a for loop

This is a basic method in which we iterate over each digit of the number using for loop, calculate its power, and add it to the result. Let's see.

internal class ArmstrongNumberInCSharpUsingForLoop
{
    static void Main()
    {
        Console.Write("Enter a number: ");
        int number = int.Parse(Console.ReadLine());

        int result = 0;
        int temporaryNumber = number;
        int count = number.ToString().Length;

        for (int temp = number; temp != 0; temp /= 10)
        {
            int digit = temp % 10;
            result += (int)Math.Pow(digit, count);
        }

        if (result == temporaryNumber)
        {
            Console.WriteLine($"Yesss, {temporaryNumber} is an Armstrong number!!");
        }
        else
        {
            Console.WriteLine($"Oohhh, {temporaryNumber} is not an Armstrong number!!");
        }

        Console.ReadLine();
    }
}

Method 3. Using Recursion

It also has the possibility of a recursive solution. The goal is to find the sum of the digits raised to the power of the total number of digits, by breaking them down recursively. Let's see.

internal class ArmstrongNumberInCSharpUsingRecursion
{
    static void Main()
    {
        Console.Write("Enter a number: ");
        int number = int.Parse(Console.ReadLine());

        int digits = number.ToString().Length;

        if (IsArmstrong(number, digits, 0, number))
        {
            Console.WriteLine($"Yesss, {number} is an Armstrong Number!!");
        }
        else
        {
            Console.WriteLine($"Oohhh, {number} is not an Armstrong Number!!");
        }
        Console.ReadLine();
    }

    static bool IsArmstrong(int number, int digits, int sum, int originalNumber)
    {
        if (number == 0)
        {
            return sum == originalNumber;
        }

        int digit = number % 10;
        sum += (int)Math.Pow(digit, digits);
        return IsArmstrong(number / 10, digits, sum, originalNumber);
    }
}

Method 4. Using Linq

If you are familiar with LINQ, you can use it to make the code more concise, although this increases the complexity compared to the previous methods. Let's see.

internal class ArmstrongNumberInCSharpUsingLinq
{
    static void Main()
    {
        Console.Write("Enter a number: ");
        int number = int.Parse(Console.ReadLine());

        int digits = number.ToString().Length;

        var sum = number.ToString()
                    .Select(c => Math.Pow(int.Parse(c.ToString()), digits))
                    .Sum();

        if (sum == number)
        {
            Console.WriteLine($"Yesss, {number} is an Armstrong Number!!");
        }
        else
        {
            Console.WriteLine($"Oohhh, {number} is not an Armstrong Number!!");
        }

        Console.ReadLine();
    }
}

Program to find Armstrong numbers between a range of numbers

In this following program, we take two inputs from the console, the start and end numbers, and use them to determine the Armstrong number between them. Let's see.

internal class FindingArmstrongNumberBetweenRangesOfNumbersInCSharp
{
    static void Main(string[] args)
    {
        Console.Write("Enter the Start Number: ");
        int StartNumber = int.Parse(Console.ReadLine());

        Console.Write("Enter the End Number: ");
        int EndNumber = int.Parse(Console.ReadLine());

        Console.WriteLine($"The Armstrong Numbers between {StartNumber} and {EndNumber} are : ");

        for (int i = StartNumber; i <= EndNumber; i++)
        {
            if (IsArmstrongNumber(i))
                Console.Write(i + ", ");
        }

        Console.ReadLine();
    }

    static bool IsArmstrongNumber(int number)
    {
        int result = 0, remainder = 0;
        int temporaryNumber = number;
        int length = number.ToString().Length;

        while (number != 0)
        {
            remainder = number % 10;
            number = number / 10;
            result += (int)Math.Pow(remainder, length);
        }

        if (result == temporaryNumber)
        {
            return true;
        }
        else
        {
            return false;
        }
    }
}

Output

See you in the next article, till then, take care and be happy learning.

You may also visit my other article,

• Explaining Palindrome Program in C#
• Character Occurrence in a String in C#
• Understanding Buzz Number in C#
• Explaining Duck Number in C#

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• c-sharp corner

Conclusion

In this article, we have discussed how to check Armstrong number in different ways using C#

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