Check if a number is magic (Recursive sum of digits is 1) in C++

Here we will see one program, that can check whether a number is magic number or not. A number is said to be magic number, when the recursive sum of the digits is 1. Suppose a number is like 50311 = 5 + 0 + 3 + 1 + 1 = 10 = 1 + 0 = 1, this is magic number.

To check whether a number is magic or not, we have to add the digits until a single-digit number is reached.

Example

 Live Demo

#include <iostream> using namespace std; int isMagicNumber(int n) {    int digit_sum = 0;    while (n > 0 || digit_sum > 9) {       if (n == 0) {          n = digit_sum;          digit_sum = 0;       }       digit_sum += n % 10;       n /= 10;    }    return (digit_sum == 1); } int main() {    int number = 50311;    if(isMagicNumber(number)){       cout << number << " is magic number";    } else {       cout << number << " is not magic number";    } }

Output

50311 is magic number