C Program to Print Sum of First N Numbers Using Recursion

Recursion in C means a function calling itself. The function dspsum recursively adds the number to the variable sum by decreasing the value of num in every call till it becomes 0.

//C program to print sum of first n numbers using recursion

#include <stdio.h>
 
void dspsum(int);
 
int main()
{
    int num;
 
    printf("Enter the Nth number: ");
    scanf("%d", &num);		//taking input from user
    dspsum(num);		//calling the recursive function 
    return 0;
}
 
void dspsum(int num) 
{
    static int sum = 0;
 
    if (num == 0)
    {
        printf("Sum of first N numbers is %d\n", sum);
        return;
    }
    else
    {
        sum += num;
        dspsum(--num);
    }

Output