### C++ program to find the sum of digits of a number:

In this post, we will learn how to find the *sum* of all digits of a number in *C++*. Our program will take one number as input from the user, calculate the sum of its digits and print it out.
We will use one *while loop* to find the digits of the given number and use one *variable* to store the sum of all the digits.
With this program, you will learn how we can use find *all digits of a number* and how we can use *for loop* to calculate something in *C++*.

### Algorithm to use:

We will use the below steps for this program:

- Get the number from the user
- Use one loop and pick the digits of the number one by one. Keep adding these digits to a
*variable*to calculate the sum. Change the*number*to*number/10* - Print out the sum.

That’s all.

To get the last digit of a number, we will use *modulo* or *%*. For example, for the number *123*:

- Current value
*123*. Get the last digit:*123%10 = 3*. Change it to*123/10 = 12*. Total sum*0+3 = 3* - Current value
*12*. Get the last digit:*12%10 = 2*. Change it to*12/10 = 1*. Total sum*3+2 = 5* - Current value
*1*. Total sum*5+1 = 6*

### C++ program:

Below is the complete C++ program:

```
#include <iostream>
using namespace std;
int main()
{
int givenNumber;
int sum = 0;
cout << "Enter a number :" << endl;
cin >> givenNumber;
while (givenNumber > 0)
{
sum += givenNumber % 10;
givenNumber = givenNumber / 10;
}
cout << "Total sum of digits :" << sum << endl;
}
```

### Explanation:

*givenNumber*is an integer variable to hold the user input number.*sum*variable is initialized as*0*to hold the sum of digits.- We are reading the number as user input using
*cin*. - Using a
*while loop*, we are finding the last digit of the number and adding it to the variable*sum*. This loop will run till the value of*givenNumber*is greater than*0*. We are also changing its value to*givenNumber / 10*on each iteration. - After the
*while loop*ends, we are printing the value of the sum.

### Sample Output:

```
Enter a number :
123
Total sum of digits :6
Enter a number :
23345
Total sum of digits :17
```