Non-Type Templates

Templates can also take small compile-time values, such as an array size.

non_type_templates.cpp

#include <array>
#include <iostream>

template <int Size>
int fillAndSum(int start) {
    std::array<int, Size> values{};
    int total = 0;

    for (int index = 0; index < Size; index++) {
        values[index] = start + index;
        total += values[index];
    }

    return total;
}

int main() {
    int start = ;

    int total = fillAndSum<3>(start);

    std::cout << "size=3" << std::endl;
    std::cout << "start=" << start << std::endl;
    std::cout << "total=" << total << std::endl;
    return 0;
}

#include <array>
#include <iostream>

template <int Size>
int fillAndSum(int start) {
    std::array<int, Size> values{};
    int total = 0;

    for (int index = 0; index < Size; index++) {
        values[index] = start + index;
        total += values[index];
    }

    return total;
}

int main() {
    int start = ;

    int total = fillAndSum<3>(start);

    std::cout << "size=3" << std::endl;
    std::cout << "start=" << start << std::endl;
    std::cout << "total=" << total << std::endl;
    return 0;
}

#include <array>
#include <iostream>

template <int Size>
int fillAndSum(int start) {
    std::array<int, Size> values{};
    int total = 0;

    for (int index = 0; index < Size; index++) {
        values[index] = start + index;
        total += values[index];
    }

    return total;
}

int main() {
    int start = ;

    int total = fillAndSum<3>(start);

    std::cout << "size=3" << std::endl;
    std::cout << "start=" << start << std::endl;
    std::cout << "total=" << total << std::endl;
    return 0;
}

non-type parameter A non-type template parameter is a value known at compile time, like the `Size` in `std::array<int, Size>`.