Armstrong Number in C++

Program in C++ To check whether the given number is Armstrong or not :

Armstrong Number: When a number is equal to the sum of the cube of each digit, then it is called an Armstrong Number.

Example: Number 153 is an Armstrong number because:

  1             5            3

= 1*1*1 + 5*5*5 + 3*3*3

=    1     +  125   +   27

=   153 = Number, Hence it is Armstrong number.
The numbers 0, 1, 153, 370, 371 and 407 are some of the Armstrong numbers.

There are various ways to check whether a number is Armstrong or not. The General algorithm for the program is given below :

 Algorithm :

Step 1: Accept a number.

Step 2: Extract each digit and cube it and add it to a variable say sum.

Step 3

 If the sum is equal to a number then display that the number is Armstrong

else display that the number is not Armstrong.

Step 3: Stop

Code 1 :

// C++ program to check whether a given number is an Armstrong number or not
#include <iostream>
using namespace std;
int main()
{
    int number, numberCopy, sum = 0;
    cout << "Enter number here: ";
    cin >> number;
    numberCopy = number;
    while (numberCopy > 0)
    {
        int lastDigit = numberCopy % 10;
        int cubeOfLastDigit = lastDigit * lastDigit * lastDigit;
        sum = sum + cubeOfLastDigit;
        numberCopy = numberCopy / 10;
    }
    if (sum == number)
        cout << "The given number " << number << " is an Armstrong Number";
    else
        cout << "The given number " << number << " is not an Armstrong Number";
    return 0;
}

Code 2 :

// C++ program to check whether a given number is an Armstrong number or not
#include <iostream>
#include <string> // included to use stoi function
using namespace std;
int main()
{
    string number;
    int sum = 0;
    cout << "Enter number here: ";
    cin >> number;
    int numberLength = number.length();
    for (int i = 0; i < numberLength; i++)
    {
        char c = number.at(i);
        int currentDigit = c - 48;
        int cubeOfDigit = (int)currentDigit * currentDigit * currentDigit;
        sum = sum + cubeOfDigit;
    }
    if (stoi(number) == sum) // stoi function is used to convert string data type to integer data type
        cout << "The given number " << number << " is an Armstrong Number";
    else
        cout << "The given number " << number << " is not an Armstrong Number";
    return 0;
}

If you have any doubt/questions related to Program, or if you want to give any suggestions, feel free to comment below. Don't forget to subscribe and share it with friends.