Question

I’m writing a C code for improving recursive functions learning. My function must calculate the average of a set of numbers received in an array. I got to calculate the sum of the numbers in the array, even to return it, same I got to calculate the average inside the function (I’ve printed it) but when I do the return, the main function always gets a trash number.

This is my code:

#include <stdio.h>
#include <stdlib.h>

float sum (int array[], int n)
{
    float f; float z=n;
    if (n==0) return (array[n]);
    f=(array[n]+sum(array,n-1));;
    return f/z;
}

int main ()
{
    int *array, n, i;
    float result;

    printf("\nDimension de tu array: ");
    scanf("%d", &n);
    array=(int *) malloc (n*sizeof (int));

    for (i=0; i<n; i++)
    {
        printf("Valor en A[%d]: ", i+1);
        scanf("%d", &array[i]);
    }
    result=sum(array,n);
    printf("\n\nEl promedio es igual a: %f ", result);
}

Answer 1

The problem is here:

return f/z;

Your function is supposed to compute the sum, but you are already dividing by the # of elements.

Change it to:

return f;

And divide by the # of elements in your main:

result = sum(array,n) / n;

And the other error is here:

if (n==0) return (array[n]);
f=(array[n]+sum(array,n-1));;

should be (and indented):

if (n==0)
    return array[n - 1];
f = array[n - 1] + sum(array,n-1);

The last index of an array is n - 1, not n.