Construction a vector from the concatenation of 2 vectors

Question

Is there a way to construct a vector as the concatenation of 2 vectors (Other than creating a helper function?)

For example:

const vector<int> first = {13};
const vector<int> second = {42};
const vector<int> concatenation = first + second;

I know that vector doesn't have an addition operator like string, but that's the behavior that I want. Such that concatenation would contain: 13 and 42.

I know that I can initialize concatenation like this, but it prevents me from making concatenation const:

vector<int> concatenation = first;
first.insert(concatenation.end(), second.cbegin(), second.cend()); 

Answer 1

No, it's not possible if you require that

• no helper function is defined, and
• the resulting vector can be declared const.

Answer 2

template<typename T>
std::vector<T> operator+(const std::vector<T>& v1, const std::vector<T>& v2){
    std::vector<T> vr(std::begin(v1), std::end(v1));
    vr.insert(std::end(vr), std::begin(v2), std::end(v2));
    return vr;
}

This does require a helper "function", but at least it allows you to use it as

const vector<int> concatenation = first + second;