C++類繼承示例

C++的子類與孫子類都實現了虛函數時，孫子類的實現會覆蓋掉子類的實現。

繼承的最主要的應用就是把不同的類放到一個數組中，然后遍歷調用同名函數。

實例如下：

#include <iostream>
#include <stdlib.h>
#include <vector> 
using namespace std;

class Parent{
	protected:
		string pname;
	public:
		Parent(string name){
			pname=name;	
		}
		
		virtual void printName(){};
};

class Child: public Parent{
	protected:
		string cname;
	public:
		Child(string name):Parent(name){
			cname=name;
		}
	
		virtual void printName(){
			cout<<"This is child, cname is "<<cname<<", pname is "<<pname<<endl;
		}
};

class GrandChild: public Child{
	private:
		string gname;
		
	public:
		GrandChild(string name):Child(name){
			gname=name;
		}
		
		virtual void printName(){
			cout<<"This is grandchild, gname is "<<gname<<", cname is "<<cname<<", pname is "<<pname<<endl;
		}
};

int main(){
	string name="C";
	Child child(name);
	name="GC";
	GrandChild gchild(name);
	
	vector<Parent*> mlist;
	mlist.push_back(dynamic_cast<Parent*>(&child));
	mlist.push_back(dynamic_cast<Parent*>(&gchild));
	
	for(int i=0;i<mlist.size();++i){
		mlist[i]->printName();
	}
}

 

注意子類與孫子類的printName函數前的virtual可加可不加，都可以正確運行……不知道哪個才是正確寫法= =