C++ 通過指針實現多態實例詳解

2020-01-26 14:12:50

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C++ 通過指針實現多態實例詳解

1.父類（DBConnector）

1）DBConnector.h

#include <string> using namespace std; class DBConnector { private:  string name; public:  DBConnector();  DBConnector(string _name);  ~DBConnector();   void show(); };

2）DBConnector.cpp

#include "DBConnector.h" #include <iostream> using namespace std;  DBConnector::DBConnector() { }  DBConnector::DBConnector(string _name) {  name = _name; }  DBConnector::~DBConnector() { }  void DBConnector::show() {  cout << name << endl; }

2.子類1（MySqlConnector）

1）MSSqlConnector.h

#pragma once #include "DBConnector.h" class MSSqlConnector :public DBConnector { public:  MSSqlConnector();  MSSqlConnector(string _name);  ~MSSqlConnector(); };

2）MSSqlConnector.cpp

#include "MSSqlConnector.h"  MSSqlConnector::MSSqlConnector() { }  MSSqlConnector::MSSqlConnector(string _name) :DBConnector(_name) {   }  MSSqlConnector::~MSSqlConnector() { }

3.子類2（MSSqlConnector）

1）MSSqlConnector.h

#pragma once #include "DBConnector.h" class MSSqlConnector :public DBConnector { public:  MSSqlConnector();  MSSqlConnector(string _name);  ~MSSqlConnector(); };

2）MSSqlConnector.pp

#include "MSSqlConnector.h"  MSSqlConnector::MSSqlConnector() { }  MSSqlConnector::MSSqlConnector(string _name) :DBConnector(_name) {   }  MSSqlConnector::~MSSqlConnector() { }

4.Test

#include "MySqlConnector.h" #include "MSSqlConnector.h" #include <iostream> #include <string> using namespace std;  void main() {  MySqlConnector mysql("mysql");  MSSqlConnector mssql("mssql");   DBConnector* p;  p = &mysql;  p->show();   p = &mssql;  p->show();    //mysql.show();  //mssql.show(); }

5.運行結果