C++ Exercises: Add up all the digits between two numbers

C++ Basic: Exercise-86 with Solution

Write a C++ program to add up all the digits between two given integers.
Add all the digits between 11 and 16.
// 11, 12, 13, 14, 15, 16
(1 + 1) + (1 +2) + (1 + 3) + (1 + 4) + (1 + 5) + (1 + 6)
= 2 + 3 + 4 + 5 + 6 + 7
= 27

Sample Data:

(5, 9) -> 35
(12, 18) -> 42
(39, 41) -> 21

Pictorial Presentation:

Sample Solution-1:

C++ Code :

#include <iostream>

using namespace std;
int test(int x, int y)
{
    int digit_sum = 0;
    for(int i = x; i <= y; ++i)
    {
        int p = i;
        while(p > 0)
        {
            digit_sum += p % 10;
            p /= 10;
        }
    }
    return digit_sum;
}

int main() {
   //int n1 = 5;
   //int n2 = 9;
   //int n1 = 12;
   //int n2 = 18;
   int n1 = 39;
   int n2 = 41;
   cout << "Add up all the digits between " << n1 << " and " << n2 << " is: ";
   cout << test(n1, n2) << endl;
}

Sample Output:

Add up all the digits between 39 and 41 is: 21

Flowchart:

Sample Solution-2:

C++ Code :

#include <iostream>

using namespace std;
int test(int x, int y)
{
   int digit_sum=0;
   int t = x;
	while(t<=y){
		x = t;
	  while(x){
		  digit_sum+=x%10;
		  x/=10;
	  }
		++t;;
	}
	return digit_sum;
}

int main() {
   //int n1 = 5;
   //int n2 = 9;
   //int n1 = 12;
   //int n2 = 18;
   int n1 = 39;
   int n2 = 41;
   cout << "Add up all the digits between " << n1 << " and " << n2 << " is: ";
   cout << test(n1, n2) << endl;
} 

Sample Output:

Add up all the digits between 39 and 41 is: 21

Flowchart:

C++ Code Editor:

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