析构函数的用法是什么？

1. 动态内存管理

析构函数常用于释放通过动态内存分配（如 new 关键字）获得的资源，以防止内存泄漏。

#include 

class DynamicMemoryExample {
private:
    int* data;

public:
    DynamicMemoryExample() {
        data = new int[10];
        std::cout << "Object constructed." << std::endl;
    }

    ~DynamicMemoryExample() {
        delete[] data;
        std::cout << "Object destructed. Memory released." << std::endl;
    }
};

int main() {
    DynamicMemoryExample* obj = new DynamicMemoryExample();
    delete obj;
    return 0;
}

2. 文件操作

析构函数可以用于在对象生命周期结束时关闭文件，确保文件资源被正确释放。

#include 
#include 

class FileExample {
private:
    std::ofstream file;

public:
    FileExample(const std::string& filename) : file(filename) {
        if (!file.is_open()) {
            std::cerr << "Failed to open file!" << std::endl;
        }
    }

    ~FileExample() {
        if (file.is_open()) {
            file.close();
            std::cout << "File closed." << std::endl;
        }
    }
};

int main() {
    FileExample obj("example.txt");
    // obj will be automatically destructed when it goes out of scope
    return 0;
}

资源管理

析构函数还可以用于释放其他类型的资源，如数据库连接、网络连接等。

#include 

class ResourceExample {
private:
    int resourceID;

public:
    ResourceExample(int id) : resourceID(id) {
        std::cout << "Resource acquired: " << resourceID << std::endl;
    }

    ~ResourceExample() {
        std::cout << "Resource released: " << resourceID << std::endl;
    }
};

int main() {
    ResourceExample obj1(1);
    ResourceExample obj2(2);
    // Objects will be automatically destructed when they go out of scope
    return 0;
}