C++ Program to find Sum of Digits in a Number

Write a C++ Program to find the Sum of Digits in a Number using a While loop with an example. Within the while loop, it divides the number into individual digits and then finds the sum of it.

Here, we used a cout statement to show you the value of the remainder and sum value in iteration wise which helps you can understand the execution.

#include<iostream>

using namespace std;

int main()
{
	int number, reminder, digitSum = 0;
	
	cout << "Please Enter the Number to calculate Sum of Digits =  ";
	cin >> number;
	
	while (number > 0)
	{
    	reminder = number % 10;
    	digitSum += reminder;
    	number = number / 10;
    	
    	cout << "\nDigit = " << reminder << " and the Digit Sum = " << digitSum;
	}
	cout << "\n\nThe Sum of all Digits in a given Number = " << digitSum;
		
 	return 0;
}

C++ Program to find Sum of Digits in a Number using a For Loop

#include<iostream>

using namespace std;

int main()
{
	int number, reminder, digitSum;
	
	cout << "Please Enter the Number to calculate Sum of Digits =  ";
	cin >> number;
	
	for(digitSum = 0; number > 0; number = number / 10)
	{
    	reminder = number % 10;
    	digitSum += reminder;
    	
    	cout << "\nDigit = " << reminder << " and the Digit Sum = " << digitSum;
	}
	cout << "\nThe Sum of all Digits in a given Number = " << digitSum;
		
 	return 0;
}

Please Enter the Number to calculate Sum of Digits =  785469

Digit = 9 and the Digit Sum = 9
Digit = 6 and the Digit Sum = 15
Digit = 4 and the Digit Sum = 19
Digit = 5 and the Digit Sum = 24
Digit = 8 and the Digit Sum = 32
Digit = 7 and the Digit Sum = 39
The Sum of all Digits in a given Number = 39

In this C++ example, we separated the logic using functions.

#include<iostream>

using namespace std;

int sumOfDigits(int number)
{
	int reminder, digitSum;
	
	for(digitSum = 0; number > 0; number = number / 10)
	{
    	reminder = number % 10;
    	digitSum += reminder;
    	
    	cout << "\nDigit = " << reminder << " and the Digit Sum = " << digitSum;
	}
	return digitSum;
}
int main()
{
	int num, digiSum;
	
	cout << "Please Enter the Number to calculate Sum of Digits =  ";
	cin >> num;
	
	digiSum = sumOfDigits(num);
	cout << "\nThe Sum of all Digits in a given Number = " << digiSum;
		
 	return 0;
}

Please Enter the Number to calculate Sum of Digits =  78932

Digit = 2 and the Digit Sum = 2
Digit = 3 and the Digit Sum = 5
Digit = 9 and the Digit Sum = 14
Digit = 8 and the Digit Sum = 22
Digit = 7 and the Digit Sum = 29
The Sum of all Digits in a given Number = 29

Sum of Digits in a Number using Recursion

#include<iostream>

using namespace std;

int sumOfDigits(int number)
{
	static int reminder, digitSum = 0;
	
	if(number > 0)
	{
    	reminder = number % 10;
    	digitSum += reminder;
    	sumOfDigits(number / 10);
    	return digitSum;
	}
	else
		return 0;
}
int main()
{
	int num, digiSum;
	
	cout << "Please Enter the Number to calculate Sum of Digits =  ";
	cin >> num;
	
	digiSum = sumOfDigits(num);
	cout << "\nThe Sum of all Digits in a given Number = " << digiSum;
		
 	return 0;
}

Please Enter the Number to calculate Sum of Digits =  248769

The Sum of all Digits in a given Number = 36