armstrong_number.cpp

 
#include <cassert>   
#include <cmath>     
#include <iostream>  
 
int number_of_digits(int num) {
    int total_digits = 0;
    while (num > 0) {
        num = num / 10;
        ++total_digits;
    }
    return total_digits;
}
 
bool is_armstrong(int number) {
    // If the number is less than 0, then it is not an armstrong number.
    if (number < 0) {
        return false;
    }
 
    int sum = 0;
    int temp = number;
    // Finding the total number of digits in the number
    int total_digits = number_of_digits(number);
    while (temp > 0) {
        int rem = temp % 10;
        // Finding each digit raised to the power total digit and add it to the
        // total sum
        sum += static_cast<int>(std::pow(rem, total_digits));
        temp = temp / 10;
    }
    return number == sum;
}
 
static void test() {
    // is_armstrong(370) returns true.
    assert(is_armstrong(370) == true);
    // is_armstrong(225) returns false.
    assert(is_armstrong(225) == false);
    // is_armstrong(-23) returns false.
    assert(is_armstrong(-23) == false);
    // is_armstrong(153) returns true.
    assert(is_armstrong(153) == true);
    // is_armstrong(0) returns true.
    assert(is_armstrong(0) == true);
    // is_armstrong(12) returns false.
    assert(is_armstrong(12) == false);
 
    std::cout << "All tests have successfully passed!\n";
}
 
int main() {
    test();  // run self-test implementations
    return 0;
}