Question

Design a class ArmNum to check if a given number is an Armstrong number or not.
[A number is said to be Armstrong if sum of its digits raised to the power of length of the number is equal to the number]
Example : 371 = 3³ + 7³ + 1³
1634 = 1⁴ + 6⁴ + 3⁴ + 4⁴
54748 = 5⁵ + 4⁵ + 7⁵ + 4⁵ + 8⁵
Thus 371, 1634 and 54748 are all examples of Armstrong numbers.

Some of the members of the class are given below:
Class name:ArmNum

Data members/instance variables:
n:to store the number
l:to store the length of the number

Methods/Member functions:

ArmNum (int nn):parameterized constructor to initialize the data member n=nn

int sum_pow(int i):returns the sum of each digit raised to the power of the length of the number using recursive technique
eg. 34 will return 3² + 4² (as the length of the number is 2)

void isArmstrong( ):checks whether the given number is an Armstrong number by invoking the function sum_pow() and displays the result with an appropriate message

Specify the class ArmNum giving details of the constructor( ), int sum_pow(int) and void isArmstrong( ). Define a main( ) function to create an object and call the functions accordingly to enable the task

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Code

				
					import java.util.Scanner;
public class ArmNum
{ 
    int n,l;

    ArmNum(int nn)
    {
        n=nn;
        l=Integer.toString(n).length();
    }

    int sum_pow(int i)
    {
        if(i==0)
        {
            return 0;
        }
        else
        {
            return (int)Math.pow(i%10,l) + sum_pow(i/10);
        }
    }

    void isArmstrong()
    { 
        if(sum_pow(n)==n)
        {
            System.out.println(n + " is an Armstrong number");
        }
        else
        {
            System.out.println(n + "is not an Armstrong number");
        }
    }
    
    public static void main()
    { 
        Scanner sc=new Scanner(System.in); 
        System.out.println("ENTER THE NUMBER");
        int num=sc.nextInt();
        ArmNum ob1=new ArmNum(num);
        ob1.isArmstrong();
}
}