C++11:

// 确保使用 C++11 标准编译
// g++ main.cpp -std=c++11 -o app

#include <iostream>
#include <string>
#include <vector>
#include <memory>   // C++11 智能指针
#include <algorithm>

// 禁用不安全函数警告（Windows 可选）
#ifdef _WIN32
#define _CRT_SECURE_NO_WARNINGS
#endif

// 命名空间
namespace MyApp {

// C++11 类示例
class Demo {
public:
    // 构造函数
    Demo(int id, const std::string& name)
        : m_id(id), m_name(name) {}

    // 常量成员函数
    void show() const {
        std::cout << "ID: " << m_id
                  << " Name: " << m_name << std::endl;
    }

    // Getter
    int id() const { return m_id; }

private:
    int m_id;
    std::string m_name;
};

} // namespace MyApp

// 主函数
int main() {
    // 1. 自动类型推导 C++11 auto
    auto num = 10;
    auto str = std::string("Hello C++11");

    // 2. 范围 for 循环 C++11
    std::vector<int> vec = {1, 2, 3, 4, 5};
    std::cout << "Vector: ";
    for (auto x : vec) {
        std::cout << x << " ";
    }
    std::cout << std::endl;

    // 3. 智能指针 unique_ptr C++11
    std::unique_ptr<MyApp::Demo> pDemo =
        std::make_unique<MyApp::Demo>(101, "TestObj");
    pDemo->show();

    // 4. Lambda 表达式 C++11
    std::cout << "Lambda sort descending: ";
    std::sort(vec.begin(), vec.end(), [](sslocal://flow/file_open?url=int+a%2C+int+b&flow_extra=eyJsaW5rX3R5cGUiOiJjb2RlX2ludGVycHJldGVyIn0=) {
        return a > b;
    });
    for (auto x : vec) {
        std::cout << x << " ";
    }
    std::cout << std::endl;

    // 5. nullptr C++11
    int* ptr = nullptr;
    if (ptr == nullptr) {
        std::cout << "ptr is null" << std::endl;
    }

    // 6. 移动语义简化示例
    std::string s1 = "hello";
    std::string s2 = std::move(s1);
    std::cout << "s2: " << s2 << std::endl;

    return 0;
}

C++23:

// 编译命令（GCC 13+/Clang 17+/VS2022）
// g++ -std=c++23 -O2 -Wall main.cpp -o app

#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <expected>    // C++23
#include <print>       // C++23
#include <ranges>      // C++20/23
#include <concepts>    // C++20

// C++20 概念约束
template<std::integral T>
T square(T x) {
    return x * x;
}

// C++23 std::expected 错误处理
std::expected<int, std::string> divide(int a, int b) noexcept {
    if (b == 0)
        return std::unexpected{"divide by zero"};
    return a / b;
}

int main() {
    // C++23 std::print / std::println
    std::println("=== C++23 Framework ===");

    // 范围 + 视图
    auto nums = std::vector{1,2,3,4,5};
    auto squared = nums
        | std::views::transform([](sslocal://flow/file_open?url=int+x&flow_extra=eyJsaW5rX3R5cGUiOiJjb2RlX2ludGVycHJldGVyIn0=) { return square(x); });

    std::print("squared: ");
    for (auto x : squared) std::print("{} ", x);
    std::println("");

    // C++23 expected 错误处理
    auto res = divide(10, 2);
    if (res) {
        std::println("10/2 = {}", *res);
    } else {
        std::println("error: {}", res.error());
    }

    // 字符串 contains (C++23)
    std::string s = "hello c++23";
    if (s.contains("c++23")) {
        std::println("string contains 'c++23'");
    }

    // if constexpr (C++17)
    if constexpr (sizeof(int) == 4) {
        std::println("int is 4 bytes");
    }

    return 0;
}

使用事例