combine two vectors c++

#include <iostream>
#include <vector>

int main() {
    std::vector<int> vec1 = {1, 2, 3};
    std::vector<int> vec2 = {4, 5, 6};

    vec1.insert(vec1.end(), vec2.begin(), vec2.end());

    for (int i : vec1) {
        std::cout << i << " ";
    }

    return 0;
}