Recursive sum of an array in C

arrayscrecursionsum

Hello I'm learning recursion in C and I am trying to find the sum of the elements.

This is my main:

int main()
{


    int arr[] = {1,2,3,4,5};
    int sum;
    sum = arr_sum(arr,4);
    printf("\nsum is:%d",sum);



    return 0;

}

And my recursive function:

//n is the last index of the array

int arr_sum( int arr[], int n )
{ // must be recursive

    int sum = 0;
    //base case:
    if (n < 0) {
        return sum;
    } else{
        sum = sum + arr[n];
    }
    //make problem smaller
    arr_sum(arr,n-1);
}

The output is:

sum is :0

Best Answer

Try this for your recursive function:

int arr_sum( int arr[], int n ) { 
  if (n < 0) {
    //base case:
    return 0;
  } else{
    return arr[n] + arr_sum(arr, n-1);
  }
}

you need to add your n-th case to your n-1 case until you get to the base case.

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