错误:在C++中的switch语句中定义二维数组时，'{‘标记前应有表达式

#include <iostream>
#include <vector>

int main() {
    std::vector<int> arr1 = {1, 2, 3};
    std::vector<int> arr2 = {4, 5, 6};

    int choice = 1;

    switch (choice) {
        case 1:
            std::cout << arr1[0] << std::endl;
            break;
        case 2:
            std::cout << arr2[0] << std::endl;
            break;
        default:
            std::cout << "Invalid choice" << std::endl;
            break;
    }

    return 0;
}