a documented example of merge sort in c

merge_sort.c

void mergeSort(int arr[], int leftIndex, int rightIndex)
{
    // 1. If the array has < 1 element do nothing. otherwise: 
    if (leftIndex < rightIndex)
    {
        // 2. determine the middle index of the array
        int midIndex = leftIndex + ((rightIndex - leftIndex) / 2);
        // 3. mergeSort the left half of the array
        mergeSort(arr, leftIndex, midIndex);
        // 4. mergeSort the left half of the array
        mergeSort(arr, midIndex + 1, rightIndex);
        // 5. now that the left half and right half of the array are sorted, merge them.
        merge(arr, leftIndex, midIndex, rightIndex);
    }
}