#include <cstddef>
#include <iostream>

// count must describe live elements; values may be null only when count is zero.
// The fixed teaching inputs have small sums representable as int.
int sum_raw(const int values[], std::size_t count) {
    int total{0};
    for (std::size_t i{0}; i < count; ++i) {
        total += values[i];
    }
    return total;
}

int main() {
    int values[]{2, 4, 6};
    std::size_t count{sizeof(values) / sizeof(values[0])};
    std::cout << sum_raw(values, count) << '\n';
    std::cout << sum_raw(nullptr, 0) << '\n';
    return 0;
}