print vector of vector c++

#include <iostream>
#include <vector>

int main() {
    std::vector<std::vector<int>> matrix = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}};

    for (const auto& row : matrix) {
        for (const auto& val : row) {
            std::cout << val << " ";
        }
        std::cout << std::endl;
    }

    return 0;
}