C++继承与虚函数，抽象类的使用

#pragma once
class IAnimal
{
public:
IAnimal(void);
~IAnimal(void);

public:
virtual void ShowMsg() = 0;
};

#include "IAnimal.h"

IAnimal::IAnimal(void)
{
}

IAnimal::~IAnimal(void)
{
}

#pragma once
#include "people.h"
class CManager :public CPeople
{
public:
CManager(void);
~CManager(void);
public:
void ShowMsg();

};

#include "Manager.h"
#include <iostream>
using namespace std;

CManager::CManager(void)
{
}

CManager::~CManager(void)
{
}

void CManager::ShowMsg()
{
cout << "Manager ShowMsg" << endl;
}

#include "People.h"
#include "IAnimal.h"
#include "Manager.h"
#include <iostream>
using namespace std;;
void main()
{

IAnimal *pPeople = NULL;
CPeople p = CPeople();
pPeople = &p;
pPeople->ShowMsg(); //输出People ShowMsg

IAnimal *pManager = new CManager();
pManager->ShowMsg();//输出Manager ShowMsg

int wait ;
cin >> wait;

}