C++ 对象构造与析构以及内存布局

主要探讨对象的构造顺序与内存的布局，主要参考来源为《Exceptional C++ Style中文版》

文中第十四条 顺序！顺序！根据文中的代码摘录如下，代码中添加了一些调试的信息。

1.首先构造虚基类子对象

2.其次构造非虚基类子对象.

3.构造成员本身

4.构造对象本身
以上同等级的构造顺序遵循从左到右的申明顺序。

但是问题出现了
问题1：这个对象X的对象内存分布是这个样子的。看上去地址是倒着分配的。首地址相近的并不是最先分配的那个对象。是个问题。。。大家可以考虑一下到底怎么分布啊？？？我的编译平台是VS2010
问题2：假如说类B1中含有某个方法，那么X对象调用的是哪块内存上的函数呢？？
我猜是左边的那个。废话少说写测试代码。
改造一下后编译竟然发现编译问题
1>e:\opensource\exceptional c++ style\example_014class\example_014class.cpp(191): error C2385: ambiguous access of 'fun'
1>          could be the 'fun' in base 'B1'
1>          or could be the 'fun' in base 'B1'
看样子编译器他决定不了X对象将会调用内存中哪块B1的函数。

是否就没有办法了呢？
想起对象模型的那本曾提到这种情况下使用 virtual的继承 。果然请看改造后的代码。
#include <map>struct classcomp {    bool operator() (const __int64& lhs, const __int64& rhs) const    {return lhs<rhs;}};std::multimap<__int64,std::string,classcomp> m_Construtor;class B1{ public:    B1()    {        std::cout<<"Constructor B1 "<<this<<'\n';        m_Construtor.insert(std::pair<__int64,std::string>((__int64)this,"Constructor B1 "));    }    virtual ~B1()    {        std::cout<<"Destructor B1 "<<this<<'\n';    }    void fun()    {        std::cout<<"fun B1 "<<this<<'\n';    }};class V1:virtual public B1{public:    V1()    {        std::cout<<"Constructor V1 "<<this<<'\n';        m_Construtor.insert(std::pair<__int64,std::string>((__int64)this,"Constructor V1 "));    }    virtual ~V1()    {        std::cout<<"Destructor V1 "<<this<<'\n';    }};class D1:virtual public V1{public:    D1()    {        std::cout<<"Constructor D1 "<<this<<'\n';        m_Construtor.insert(std::pair<__int64,std::string>((__int64)this,"Constructor D1 "));    }    virtual ~D1()    {        std::cout<<"Destructor D1 "<<this<<'\n';    }};class B2{public:    B2()    {        std::cout<<"Constructor B2 "<<this<<'\n';        m_Construtor.insert(std::pair<__int64,std::string>((__int64)this,"Constructor B2 "));    }    virtual ~B2()    {        std::cout<<"Destructor B2 "<<this<<'\n';    }};class B3{public:    B3()    {        std::cout<<"Constructor B3 "<<this<<'\n';        m_Construtor.insert(std::pair<__int64,std::string>((__int64)this,"Constructor B3 "));    }    virtual ~B3()    {        std::cout<<"Destructor B3 "<<this<<'\n';    }};class V2:virtual public B1,public B2{public:    V2()    {        std::cout<<"Constructor V2 "<<this<<'\n';        m_Construtor.insert(std::pair<__int64,std::string>((__int64)this,"Constructor V2 "));    }    virtual ~V2()    {        std::cout<<"Destructor V2 "<<this<<'\n';    }};class D2:public B3,virtual public V2{public:    D2()    {        std::cout<<"Constructor D2 "<<this<<'\n';        m_Construtor.insert(std::pair<__int64,std::string>((__int64)this,"Constructor D2 "));    }    virtual ~D2()    {        std::cout<<"Destructor D2 "<<this<<'\n';    }};class M1{public:    M1()    {        std::cout<<"Constructor M1 "<<this<<'\n';        m_Construtor.insert(std::pair<__int64,std::string>((__int64)this,"Constructor M1 "));    }    virtual ~M1()    {        std::cout<<"Destructor M1 "<<this<<'\n';    }};class M2{public:    M2()    {        std::cout<<"Constructor M2 "<<this<<'\n';        m_Construtor.insert(std::pair<__int64,std::string>((__int64)this,"Constructor M2 "));    }    virtual ~M2()    {        std::cout<<"Destructor M2 "<<this<<'\n';    }};class X: public D1, public D2{public:    X()    {        std::cout<<"Constructor X "<<this<<'\n';        m_Construtor.insert(std::pair<__int64,std::string>((__int64)this,"Constructor X "));    }    virtual ~X()    {        std::cout<<"Destructor X "<<this<<'\n';    }private:    M1 _m1;    M2 _m2;};int _tmain(int argc, _TCHAR* argv[]){    //B b;    int  i;    X *pX = new X;    std::cout<<"--------------------------------------------"<<'\n';    pX->fun();    std::cout<<"--------------------------------------------"<<'\n';    cout.setf(ios::showbase | ios::uppercase); //设置基指示符输出和数值中的字母大写输出    std::multimap<__int64,std::string,classcomp> ::iterator iter;    for (iter = m_Construtor.begin();iter != m_Construtor.end();++iter)//遍历    {        cout<<std::hex<<(*iter).first<<"  "<<(*iter).second<<endl;    }    std::cout<<"--------------------------------------------"<<'\n';    delete pX;    pX = NULL;    std::cin>>i;return 0;}
运行结果：
Constructor B1 00127F94
Constructor V1 00127F98
Constructor B2 00127F9C
Constructor V2 00127F9C
Constructor D1 00127F88
Constructor B3 00127F80
Constructor D2 00127F80
Constructor M1 00127F8C
Constructor M2 00127F90
Constructor X 00127F80
--------------------------------------------
fun B1 00127F94
--------------------------------------------
0X127F80  Constructor B3
0X127F80  Constructor D2
0X127F80  Constructor X
0X127F88  Constructor D1
0X127F8C  Constructor M1
0X127F90  Constructor M2
0X127F94  Constructor B1
0X127F98  Constructor V1
0X127F9C  Constructor B2
0X127F9C  Constructor V2
--------------------------------------------
Destructor X 00127F80
Destructor M2 00127F90
Destructor M1 00127F8C
Destructor D2 00127F80
Destructor B3 00127F80
Destructor D1 00127F88
Destructor V2 00127F9C
Destructor B2 00127F9C
Destructor V1 00127F98
Destructor B1 00127F94
发现类B1还少构造了一次。哈哈~~果然很强大啊。。