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c++11variadic-templates

How to assign variadic template arguments to std::array

I have an std::array and I have a variadic template function with the number of parameters that matches the size of the array. I need to assign the arguments to the elements of the array. In other words, in the code below I wish a to get values {1, 2, 3} and b to get values {1, 2, 3, 4, 5}

std::array<int, 3> a;
std::array<int, 5> b;

assign_values(a, 1, 2, 3);
assign_values(b, 1, 2, 3, 4, 5);

The question is how to implement the assign_values variadic template function.

I'm limited with the C++14 version.

Update: The arguments can be of different types: assign_values(b, 1, 2u, 3., '4', 5l);

Solution

  • Sth like this:

    template<class T, size_t N, class ... Values>
void assign_values(std::array<T,N>& arr, Values... vals) {
    static_assert(N == sizeof...(vals));
    int j = 0;
    for (auto i : std::initializer_list< std::common_type_t<Values...> >{vals...})
        arr[j++] = i;
}

    Demo