Here is an example to calculate the sum of digits in C++ language,
Example
#include<iostream>
using namespace std;
int main() {
int x, s = 0;
cout << "Enter the number : ";
cin >> x;
while (x != 0) {
s = s + x % 10;
x = x / 10;
}
cout << "\nThe sum of the digits : "<< s;
}Output
Enter the number : 236214828 The sum of the digits : 36
In the above program, two variables x and s are declared and s is initialized with zero. The number is entered by the user and when number is not equal to zero, it will sum up the digits of number.
while (x != 0) {
s = s + x % 10;
x = x / 10;
}