Adding Natural Numbers By Recursion in C++


Write a C++ program that uses recursive function to find the sum of natural numbers.

Click Here to View the Solution:
#include <iostream>
using namespace std;
int sum(int num);
int main()
    int num;
    cout << "Insert a positive number: ";
    cin >> num;
    cout << "Its recursive sum is: " << sum(num);
    return 0;
int sum(int num)
    if(num != 0)
    return num + sum(num - 1);
    return 0;
Click Here to View the Output:
Insert a positive number: 20
Its recursive sum is: 210
Click Here to View the Explanation:
  • This program operated by requesting the user to enter a number num.
  • num is passed to sum () function. The sum is saved and added to the answer of the addition result of num-1. num is decremented by 1.
  • The process continues until num is decreased to 0.
  • The answer is calculated by returning each addition result.