C++中派生类的结构和析构顺序详解

派生类因为要挪用基类, 所以结构和析构都是凭据必然顺序举办;

结构的顺序是: 基(base) -> 派生(derived);即先结构基类, 再结构派生类;

因为 基类 是独立于派生类的, 即不会挪用派生类中的工具, 所以应该先被生成;

假如派生类先于基类生成, 则因为无法挪用基类资源, 大概生成失败;

析构的顺序是: 派生(derived) -> 基(base); 即先释放派生类, 再释放基类;

因为 派生类 需要先释放挪用的基类资源, 所以应该优先释放;

假如基类先析构, 则有大概某些资源被派生类占用, 大概导致析构失败;

派生类的结构和析构顺序正好相反;

代码:

/* 
 * CppPrimer.cpp 
 * 
 *  Created on: 2013.11.12 
 *      Author: Caroline 
 */
      
/*eclipse cdt*/
      
#include <iostream>  
#include <string>  
#include <vector>  
#include <memory>  
#include <cstddef>  
      
using namespace std;  
      
class Quote {  
public:  
    //Quote() = default;  
    Quote() {  
        std::cout << "this is Quote constructor" << std::endl;  
    }  
    Quote (const std::string& book, double sales_price) :  
        bookNo (book), price (sales_price) {}  
    std::string isbn() const { return bookNo; }  
    virtual double net_price (std::size_t n) const { return n* price; } //虚函数  
    //virtual ~Quote() = default; //动态绑定析构器  
    virtual ~Quote() {  
        std::cout << "this is Quote destructor" << std::endl;  
    }  
private:  
    std::string bookNo;  
protected: //受掩护范例  
    double price = 0.0;  
};  
/*
this is Quote constructor  
this is Disc_quote constructor  
this is Bulk_quote constructor  
this is Bulk_quote destructor  
this is Disc_quote destructor  
this is Quote destructor
作者：csdn博客 Spike_King