In this program, You will learn how to find the sum of digits of a number using call by Reference in C++.

```
Call by Reference
void sumOfDigit(int n, int *sum) {
//statement
}
```

## Example: How to find the sum of digits of a number using call by Reference in C++.

```
#include<iostream>
using namespace std;
void sumOfDigit(int n, int *sum) {
int r;
while (n > 0) {
r = n % 10;
*sum = *sum + r;
n = n / 10;
}
}
int main() {
int n, sum = 0;
cout << "Enter a number:";
cin >> n;
sumOfDigit(n, &sum);
cout << "Sum of digits:" << sum;
return 0;
}
```

#### Output:

```
Enter a number:1234
Sum of digits:10
```