armstrong_number.cpp File Reference

Program to check if a number is an Armstrong/Narcissistic number in decimal system. More...

#include <cassert>
#include <cmath>
#include <iostream>

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Functions
int	number_of_digits (int num)
bool	is_armstrong (int number)
void	test ()
int	main ()

Detailed Description

Program to check if a number is an Armstrong/Narcissistic number in decimal system.

Armstrong number or Narcissistic number is a number that is the sum of its own digits raised to the power of the number of digits.

Author

iamnambiar

Function Documentation

is_armstrong()

bool is_armstrong

(

int

number

)

Function to check whether the number is armstrong number or not.

Parameters

num

Number

Returns

true if the number is armstrong.

false if the number is not armstrong.

                              {
    // If the number is less than 0, then it is not a 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 = sum + std::pow(rem, total_digits);
        temp = temp / 10;
    }
    return number == sum;
}

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main()

int main

(

void

)

Main Function

           {
    test();
    return 0;
}

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number_of_digits()

int number_of_digits

(

int

num

)

Function to calculate the total number of digits in the number.

Parameters

num

Number

Returns

Total number of digits.

                              {
    int total_digits = 0;
    while (num > 0) {
        num = num / 10;
        ++total_digits;
    }
    return total_digits;
}

test()

void test

(

)

Function for testing the is_armstrong() function with all the test cases.

            {
    // 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);
}

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