• 抽象类，类中包含纯虚函数的为抽象类，其中抽象类的子类必须实现抽象类的纯虚函数方法。
  • 抽象类无法实例化
  • 虚函数，子类可以实现或者不实现该方法都可以
  • 如果父类调用子类的基类指针时，有虚函数的则使用子类的实现虚函数的类。

具体实例代码：
头文件：

#include "stdafx.h"

class People{
public:
  virtual bool getOpenSex() = 0;
  virtual void setHeight(int height); //设置身高
  virtual void setWeight(int weight);//设置体重
private:
  int m_height;
  int m_weight;
};

class Man:public People
{
public:
  //virtual void setHeight(int height);
  bool getOpenSex(); //true:man false:woman
private:
  int sex_attr; //sex-attribute
};

class WoMan:public People
{
public:
  //virtual void setHeight(int height);
  bool getOpenSex(); //true:man false:woman
private:
  int sex_attr; //sex-attribute
};

class Baby{
public:
  virtual void BabyFace(); //虚函数默认调用子函数方法
};

class AngleBaby:public Baby
{
public:
  virtual void BabyFace();
};

实现文件：

// AbstractClassDemo.cpp : 定义控制台应用程序的入口点。
// C++ 抽象类使用：
// 抽象类：即类中包含纯虚函数，抽象类不能被实例化

#include "stdafx.h"
#include "PeopleDemo.h"

using namespace std;

void People::setHeight(int height)
{
  cout << "I want to say nothing height!" << endl;
  m_height = height;
}

void People::setWeight(int weight)
{
  cout << "I want to say nothing!" << endl;
  m_weight = weight;
}

bool Man::getOpenSex()
{
  cout << "It is a man!" << endl;
  return true;
}

bool WoMan::getOpenSex()
{
  cout << "It is a woman!" << endl;
  return true;
}

void Baby::BabyFace()
{
  cout << "You are a baby!" << endl;
}

void AngleBaby::BabyFace(){
  cout << "You are Angle Baby!" << endl;
}

//void Man::setHeight(int height)
//{
//  cout << "man height" << endl;
//  return ;
//}

//void WoMan::setHeight(int height)
//{
//  cout << "woman height" << endl;
//  return ;
//}

int _tmain(int argc, _TCHAR* argv[])
{
  Man xx;
  xx.setHeight(111);
  xx.getOpenSex();
  WoMan *ss = new WoMan();
  ss->getOpenSex();
  ss->setHeight(1113);
  delete ss;
  Baby * mybaby = new AngleBaby();
  mybaby->BabyFace();
  system("pause");
  return 0;
}

运行结果：

C++ 虚函数，纯虚函数，抽象类整理_抽象类