Java Program To Find Armstrong Number Between Two Intervals

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Program To Find Armstrong Number Between Two Number

In this article we will see different ways to find Armstrong number between two numbers.

Armstrong Number:

A n digit number in which cube sum of all It’s digit is equal to the number it self .

For example :

407 is an Armstrong number since (4*4*4) + (0*0*0)+ (7*7*7)= 407.

3 Different approaches to do it.

Checking Armstrong number using while loop
Checking Armstrong number using for loop
Checking Armstrong number using recursion

Method 1: Checking Armstrong number using while loop

Using while loop we can check Armstrong numbers within a range.

Approach:

Enter first number .
Enter second number .
Traverse between 2 number using for loop .
In that loop do following step,
Using while loop Calculate its cube sum of digits .
Compare with the original number and print according to it .

Program:

import java.util.Scanner;
public class Main
{  
    public static void main(String[] args)
    {  
        // CREATING OBJECT 
        Scanner sc = new Scanner(System.in);  
        // TAKING RANGE INPUT FORM USER 
        System.out.print("Enter the 1st  number : ");  
        int n1= sc.nextInt();
        System.out.print("Enter the 2nd number : ");  
        int n2= sc.nextInt();
        System.out.print("Amstrong number are : ");
       //traversing between two number 
        for( int i=n1; i<=n2;i++)
        {
    // storing original value in temp variable
            int k=i;
            int temp=0;
    // calculating the cube sum of digit of that number  
            while(k>0)
                {
            	    int a=k%10;
                    temp=temp+(a*a*a);
            	    k=k/10;
        	    }
        	 if (temp==i) 
            System.out.println(" "+ temp);
        }   
    }
}

Output:

Enter the 1st number : 1
Enter the 2nd number : 1000
Armstrong number are : 
1
153
370
371
407

Method 2: Checking Armstrong number using for loop

Using for loop we can check Armstrong numbers within a range.

Approach:

Enter first number .
Enter second number .
Traverse between 2 number using for loop .
In that loop do following step,
Using for loop Calculate its cube sum of digits .
Compare with the original number and print according to it

Program:

import java.util.Scanner;
public class Main
{  
    public static void main(String[] args)
    {  
        // CREATING OBJECT 
        Scanner sc = new Scanner(System.in);  
        // TAKING RANGE INPUT FORM USER 
        System.out.print("Enter the 1st  number : ");  
        int n1= sc.nextInt();
        System.out.print("Enter the 2nd number : ");  
        int n2= sc.nextInt();
        System.out.print("Amstrong number are : ");
        //traversing between two number 
        for( int i=n1; i<=n2;i++)  
        {
            // storing original value in temp variable
            int k=i;
            int temp=0;
        // calculating the cube sum of digit of that number  
           for( ;k!=0;k/=10 )
        	{
            	int a=k%10;
            	temp=temp+(a*a*a);
        	}
        	 if (temp==i)
            System.out.println(" "+ temp);
        }	   
    }
}

Output:

Enter the 1st number : 1
Enter the 2nd number : 1000
Armstrong number are : 
1
153
370
371
407

Method 3: Checking Armstrong number using recursion

Using for loop we can check Armstrong numbers within a range.

Approach :

Create a function that will calculate and return the sum of cube of digit .
Enter first number .
Enter second number .
Traverse between 2 number using for loop .
In that loop do following step,
Parse the entered value to that function and store it to a variable .
Compare with the original number and print according to it .

Program :

import java.util.Scanner;
public class Main
{  
    int fams(int n,int a)
    {   //calculating cube sum of digits
        if(n!=0)
            {
            	int x=n%10;
            	a=a+(x*x*x);
            	n/=10 ;
            	return fams(n,a);
            }
        return a;
    }
    public static void main(String[] args)
    {  
        // CREATING OBJECT 
        Scanner sc = new Scanner(System.in);  
        // TAKING RANGE INPUT FORM USER 
        System.out.print("Enter the 1st  number : ");  
        int n1= sc.nextInt();
        System.out.print("Enter the 2nd number : ");  
        int n2= sc.nextInt();
        System.out.print("Amstrong number are : ");
        
        // creating the object of main function 
        Main ams= new Main();
        // traversing between two number 
        for( int i=n1; i<=n2;i++)
            {
                // storing original value in temp variable 
                int k=i;
                //parsing value to the function 
                int temp=ams.fams(i,0);
                // comparing with the orginal value and printing  it.
                if (k==temp)
                    System.out.println(" " +k); 
            }
    }  
}

Output: 

Enter the 1st number : 1 
Enter the 2nd number : 1000 
Armstrong number are : 
1 
153 
370 
371 
407

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