C++中关于class B:A与Class B::A问题

#include<iostream>

class A
{
public:
void print()
{ std::cout<<"A::print()"<<std::endl; }
};

class B:A //这里等价于class B:private A 即B继承A的方式为私有继承
{
public:
void test()
{
print();
std::cout<<"B::test()"<<std::endl; 
}
};

int main()
{

B b;
b.test();
return 0;
}

//File:TestSample.h
#include<boost/smart_ptr.hpp>

class TestSample
{
private:
class TestSampleImpl;
boost::shared_ptr<TestSampleImpl> m_ptrImpl;

public:
TestSample();
~TestSample();

void Display();    
};

//////////////////////////////////////////
//File:TestSample.cpp
#include "TestSample.h"
#include "TestSampleImpl.h"
#include<boost/make_shared.hpp>

TestSample::TestSample()
{
m_ptrImpl=boost::make_shared<TestSampleImpl>();
}

TestSample::~TestSample()
{

}

void TestSample::Display()
{
m_ptrImpl->Display();

}

///////////////////////////////////////////
//File:TestSampleImpl.h
#include "TestSample.h"

class TestSample::TestSampleImpl
{
public:
TestSampleImpl(){}
~TestSampleImpl(){}

void Display();    
};

////////////////////////////////////////
//File:TestSampleImpl.cpp
#include "TestSampleImpl.h"
#include<iostream>

void TestSample::TestSampleImpl::Display()
{
std::cout<<"TestSampleImpl::Display()"<<std::endl;
}


////////////////////////////////////////
//File:main.cpp
#include"TestSample.h"

int main(int argc,char *argv[])
{
TestSample inst;
inst.Display();

return 0;
}