CODEWITHSUNDEEP
javanumbers
vivek sharma
vivek sharma

Reputation: 23

Issues while executing Armstrong number program

I am trying out a code that finds out whether a number entered is Armstrong or not. Here is the Code:

import java.util.*;

public class Arm {
    int a, b, c;

    void m1() {
        Scanner obj = new Scanner(System.in);
        System.out.println("Enter a number");
        int number = obj.nextInt();
        number = (100 * a) + (10 * b) + (1 * c);
        if ((a * a * a) + (b * b * b) + (c * c * c) == number) {
            System.out.println("number is armstrong");
        } else {
            System.out.println("number is not armstrong");
        }
    }

    public static void main(String args[]) {
        Arm obj = new Arm();
        obj.m1();
    }
}

Here the value of a,b and c comes out to be zero. But that is not the correct result. Say if we enter a number 345. Then a,b and c should be 3, 4 and 5 respectively. Please guide.

Upvotes: 0

Views: 158

Answers (1)

Uma Kanth
Uma Kanth

Reputation: 5629

That is not how you calculate a, b, c.

To find a,b,c we repeatedly divide by 10 and get the remainder by modulus.

int digit = 0;
int sum = 0;
while(num > 0)
{
 digit = num % 10;
 sum += Math.pow(digit, 3);
num = num/10;
}

Why do we use / and %

Consider 345.

Now to get the last digit what can be done?

What does a modulus return? The remainder, so If we perform %10 we get the last digit.

345 % 10 = 5

Now we want the second last digit.

So we divide the number by 10, so we get the quotient

345 / 10 = 34

Now again if we can perform the modulus we get the 4 and so on..

What does 100 * a + 10 * b + 1 * c do?

That is used to get a number if we have the individual digits.

Suppose we have 3, 4, 5 we know that we get 345 out of it but how do we do it?

3 * 100 = 300
4 * 10 = 40
5 * 1 = 5
-----------
300 + 40 + 5 = 345

Now to complete your whole program.

public boolean isAmg(int num)
{
   int digit = 0;
   int sum = 0;
   int copyNum = num; //used to check at the last 
   while(num > 0)
   {
      digit = num % 10;
      sum += Math.pow(digit, 3);
      num = num / 10;
    }
    return sum == copyNum;
}

Upvotes: 2

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