ISC COMPUTER SCIENCE THEORY PAPER JAVA PROGRAMS -2019 Question 7

 

ISC COMPUTER SCIENCE THEORY PAPER JAVA PROGRAMS -2019 Question 7            

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   = 3^3 + 7^3 + 1^3

                 1634  = 1^44 + 6^4 + 3^4 + 4^4  

              54748 = 5^5 + 4^5 + 7^5 + 4^5 + 8^5       

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 3^2 + 4^2 (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.         

 

 

import java.util.*;

public class ISC2019Q7 {

       public static void main(String[] args) {

          int m,n;

          Scanner in = new Scanner(System.in);

          do {

                 System.out.println("INPUT: Enter the value n:");

                 n= in.nextInt();

                 if(n <= 0)

                            System.out.println("Wrong input, please try again:");

          }while (n <= 0);    

          ArmNum obj = new ArmNum(n);

          obj.isArmstrong();

          in.close();

      }

}

 

class ArmNum {

      

              public void isArmstrong() {

                     if (nn == sum_pow(nn))

                           System.out.println(nn+" is an Armstrong Number");

                     else

                           System.out.println(nn+" is not an Armstrong Number");

                    

              }

             

              public int sum_pow(int i) {

                     if ( i <= 0)

                           return sum_power;

                     else

                           return (sum_power+(int)Math.pow(i%10, l)+sum_pow(i/10)); // using recursion

              }

             

              private void lengthofNumber() { // calculates the length of the number

                     int temp=nn;

                     do {

                           temp /=10;

                           l++;

                     }while(temp > 0);

              }

             

              ArmNum( int nn){

                     this.nn = nn;

                     l=0;

                     sum_power= 0;

                     lengthofNumber();

              }

             

              private int nn;

              private int l;

              private int sum_power;

}