# C program to find sum of even or odd number in given range using recursion

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

Example

Input

```Input lower limit: 1
Input upper limit: 100```

Output

`Sum of even numbers between 1 to 100 = 2550`

## Required knowledge

Finding sum of even or odd numbers in range is almost similar to previous program we did.

## Declare recursive function to find sum of even number

1. First give a meaningful name to our function, say `sumOfEvenOdd()`.
2. Next the function accepts two integer values from user i.e. start and end range. Hence, update function declaration to `sumOfEvenOdd(int start, int end);`.
3. Finally, after calculating sum of even or odd numbers the function must return it to the caller. Hence, return type of the function must be `int`.

Final function declaration to find sum of all even or odd numbers in given range is - `int sumOfEvenOdd(int start, int end);`.

## Program to find sum of even or odd numbers using recursion

``````/**
* C program to find sum of all even or odd numbers in given range using recursion
*/

#include <stdio.h>

int sumOfEvenOdd(int start, int end);

int main()
{
int start, end, sum;

/* Input lower and upper limit from user */
printf("Enter lower limit: ");
scanf("%d", &start);
printf("Enter upper limit: ");
scanf("%d", &end);

printf("Sum of even/odd numbers between %d to %d = %d\n", start, end, sumOfEvenOdd(start, end));

return 0;
}

/**
* Find sum of all even or odd numbers recursively.
*/
int sumOfEvenOdd(int start, int end)
{
/* Base condition */
if(start > end)
return 0;
else
return (start + sumOfEvenOdd(start + 2, end));
}``````

Output

```Enter lower limit: 2
Enter upper limit: 100
Sum of even/odd numbers between 2 to 100 = 2550```

Happy coding 😉 