析构函数的用法是什么？

迷南。 2023-10-14 18:17 63阅读 0赞

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 <iostream>
    
    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;
    }

1.  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 <iostream>
    #include <fstream>
    
    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 <iostream>
    
    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;
    }