用于在C++ std :: <vector>容器中存储多种类型的结构的模式

#include<iostream>
#include<vector>
#include<variant>

int main() {
    std::vector<std::variant<int, double, std::string>> vec;
    vec.push_back(42);
    vec.push_back(3.14);
    vec.push_back("hello");

    for (const auto& item : vec) {
        std::visit([](const auto& value) {
            using T = std::decay_t<decltype(value)>;
            if constexpr (std::is_same_v<T, int>) {
                std::cout << "int: "<< value<< std::endl;
            } else if constexpr (std::is_same_v<T, double>) {
                std::cout << "double: "<< value<< std::endl;
            } else if constexpr (std::is_same_v<T, std::string>) {
                std::cout << "string: "<< value<< std::endl;
            }
        }, item);
    }

    return 0;
}

#include<iostream>
#include<vector>
#include <any>

int main() {
    std::vector<std::any> vec;
    vec.push_back(42);
    vec.push_back(3.14);
    vec.push_back("hello");

    for (const auto& item : vec) {
        if (item.type() == typeid(int)) {
            std::cout << "int: "<< std::any_cast<int>(item)<< std::endl;
        } else if (item.type() == typeid(double)) {
            std::cout << "double: "<< std::any_cast<double>(item)<< std::endl;
        } else if (item.type() == typeid(std::string)) {
            std::cout << "string: "<< std::any_cast<std::string>(item)<< std::endl;
        }
    }

    return 0;
}