check_armstrong.cpp

#include <bits/stdc++.h>
using namespace std;
 
/* Function to calculate x raised to the power y */
int power(int x, unsigned int y)
{
    if (y == 0)
        return 1;
    if (y % 2 == 0)
        return power(x, y / 2) * power(x, y / 2);
    return x * power(x, y / 2) * power(x, y / 2);
}
 
/* Function to calculate order of the number */
int order(int x)
{
    int n = 0;
    while (x) {
        n++;
        x = x / 10;
    }
    return n;
}
 
// Function to check whether the given number is
// Armstrong number or not
bool isArmstrong(int x)
{
    // Calling order function
    int n = order(x);
    int temp = x, sum = 0;
    while (temp) {
        int r = temp % 10;
        sum += power(r, n);
        temp = temp / 10;
    }
 
    // If satisfies Armstrong condition
    return (sum == x);
}
 
// Driver Program
int main()
{
    int x = 153;
    cout << boolalpha << isArmstrong(x) << endl;
    x = 1253;
    cout << boolalpha << isArmstrong(x) << endl;
    return 0;
}