假定多层继承的各类之间的关系如下图。假定派生类不override基类的虚函数，即Base2不override Base1中声明的虚函数vfBase1()，Base3不override Base2中声明的虚函数vfBase2()，Derived不override Base3中声明的虚函数vfBase3()。

  

代码如下

#include 
     
      using namespace std;class Base1{public:    int m_base1;    inline virtual void vfBase1_1()    {        cout << "This is in Base1::vfBase1_1()" << endl;    }};class Base2 : public Base1{public:    int m_base2;    inline virtual void vfBase2_1()    {        cout << "This is in Base2::vfBase2_1()" << endl;    }};class Base3 : public Base2{public:    int m_Base3;    inline virtual void vfBase3_1()    {        cout << "This is in Base3::vfBase3_1()" << endl;    }};class Derived : public Base3{public:    int m_derived;    inline virtual void fd()    {        cout << "This is in Derived::fd()" << endl;    }};typedef void (*VFun)(void);template
      
       VFun virtualFunctionPointer(T* b, int i){    return (VFun)(*((int*)(*(int*)b) + i));}int main(void){    Derived d;    cout << "The size of Derived object = \t" << sizeof(Derived) << endl;    cout << endl;    cout << "1st virtual function table: " << endl;    int i = 0;    while(virtualFunctionPointer(&d, i))    {        VFun pVF = virtualFunctionPointer(&d, i++);        pVF();    }    return 0;}
      
     

运行结果：

Derived对象的memory layout图解如下：

 

（注意：单重继承只有一个虚函数表）