// 28_new_delete.cpp
// 动态内存实战演练：裸指针、智能指针、自定义删除器对比
// 泄漏检测可加 -fsanitize=address；取消 raw_pointer_demo 里提前返回的注释即可观察 ASan 报告

#include <iostream>
#include <memory>

void raw_pointer_demo() {
    std::cout << "=== 裸指针版本 ===\n";
    int* p = new int(42);
    std::cout << "值: " << *p << "\n";

    int* arr = new int[5];
    for (int i = 0; i < 5; ++i) {
        arr[i] = i * 10;
    }

    // 模拟提前返回（取消注释以观察泄漏）:
    // if (true) return;

    delete p;
    delete[] arr;
    std::cout << "手动释放完成\n";
}

void smart_pointer_demo() {
    std::cout << "\n=== 智能指针版本 ===\n";
    auto p = std::make_unique<int>(42);
    std::cout << "值: " << *p << "\n";
    auto arr = std::make_unique<int[]>(5);
    for (int i = 0; i < 5; ++i) {
        arr[i] = i * 10;
    }
    // 不管以何种方式离开（正常返回、提前 return、异常）
    // 析构函数都会自动释放内存
    std::cout << "离开作用域时自动释放\n";
}

void custom_deleter_demo() {
    std::cout << "\n=== 自定义删除器 ===\n";
    auto deleter = [](int* ptr) {
        std::cout << "自定义删除器被调用，值为: " << *ptr << "\n";
        delete ptr;
    };
    std::unique_ptr<int, decltype(deleter)> p(new int(99), deleter);
    std::cout << "值: " << *p << "\n";
}

int main() {
    raw_pointer_demo();
    smart_pointer_demo();
    custom_deleter_demo();
    std::cout << "\n程序结束\n";
    return 0;
}