Write a recursive function in C programming to find sum of all natural numbers between 1 to n. How to find sum of all natural numbers in C programming using recursion. Finding sum of all natural numbers using between a given range using recursion.

Input upper limit to find sum: 100

Output: Sum of natural numbers from 1 to 10 = 55

sum(0) = 0

sum(n) = n + sum(n-1)

Happy coding ;)

**Example:**Input upper limit to find sum: 100

Output: Sum of natural numbers from 1 to 10 = 55

### Required knowledge

Basic C programming, Function, Recursion### Logic to find sum of natural numbers using recursion

If you are done with how to find sum of natural numbers from 1 to n using loop then logic to this program would not be difficult. Below is the recursion base condition for the recursive program to find sum of first n natural numbers:sum(0) = 0

**{Base condition}**sum(n) = n + sum(n-1)

### Program to find sum of natural numbers using recursion

/** * C program to find sum of natural numbers from 1 to n using recursion */ #include <stdio.h> /* Function declaration */ int sum(int N); int main() { int n, s; printf("Enter upper limit to find sum: "); scanf("%d", &n); s = sum(n); //Calls sum() function and stores the result in s printf("Sum of natural numbers from 1 to %d = %d", n, s); return 0; } /** * Recursively finds the sum of natural number from 1 to n */ int sum(int N) { if(N == 0) return 0; else return (N + sum(N-1)); }

Output

Enter upper limit to find sum: 100

Sum of natural numbers from 1 to 100 = 5050

Sum of natural numbers from 1 to 100 = 5050

Happy coding ;)

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