#include <array>
#include <cassert>
#include <iostream>
#include <span>
#include <string>
#include <string_view>

std::string_view first_field(std::string_view text) {
    return text.substr(0, text.find(','));
}
void increment(std::span<int> values) {
    for (int& n : values) ++n;
}

int main() {
    std::string text = "alpha,beta";
    std::string_view field = first_field(text);
    assert(field == "alpha" && field.size() == 5);
    std::array<int, 3> values{1, 2, 3};
    increment(std::span<int>(values).subspan(1));
    std::span<const int> read_only(values);
    assert(read_only[0] == 1 && read_only[1] == 3 && read_only[2] == 4);
    std::cout << field << ' ' << read_only[1] << ' ' << read_only[2] << '\n';
}