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

/* defining array members count */
#define ARRAY_COUNT ((int)10)

/* delcaring functions */
void fill_array(int *array);
void print_array(int *array);
float find_mean(int *array);

/* entry point */
int main(void)
{
    /* preparing randomizer */
    srand(time(NULL));
    /* declaring array */
    int array[ARRAY_COUNT];

    /* working */
    fill_array(array);
    print_array(array);
    printf("mean: %0.2f\n", find_mean(array));

    /* waiting for exit */
    return system("pause");
}

/* filling array with rundom numbers */
void fill_array(int *array)
{
    /* we don't want to work with NULLs */
    if (array == NULL)
    {
        printf("Array is NULL pointer\n");
        return;
    }

    /* generating rundoms and writing tham to array */
    for (int i = 0; i < ARRAY_COUNT; i++)
        array[i] = rand() % 100 + 1;
}

/* printing array to stdout */
void print_array(int *array)
{
    printf("=====\tARRAY\t=====\n");
    /* we don't want to work with NULLs */
    if (array == NULL)
    {
        printf("Array is NULL pointer\n");
        return;
    }

    for (int i = 0; i < ARRAY_COUNT; i++)
        printf("ARR[%2d] = %3d\n", i+1, array[i]);
    printf("=====================\n");
}

/* finding mean */
float find_mean(int *array)
{
    /* we don't want to work with NULLs */
    if (array == NULL)
    {
        printf("Array is NULL pointer\n");
        return -1;
    }

    float mean = .0;
    int count = 0;

    for (int i = 0; i < ARRAY_COUNT; i++)
    {
        if (array[i] % 2 == 0) {
            mean += array[i];
            count++;
        }
    }

    return mean/count;
}