保證基類的也被調(diào)用。什么情況下使用比較好呢。
#include <iostream>
using namespace std;
class Base{
private:
int num1;
public:
Base():num1(10)
{
}
virtual ~Base()
{
cout<<"base"<<endl;
}
};
class Dervied:public Base{
private:
int num2;
public:
Dervied():num2(1)
{
}
~Dervied()
{
cout<<"Dervied"<<endl;
}
};
int main()
{
Base *pBase = new Dervied();
delete pBase;
}
結(jié)果會(huì)
Dervied
Base
#include<iostream>
using namespace std;
class ClxBase
{
public:
ClxBase() {};
~ClxBase() {cout<<"Do base class destruct"<<endl;};
};
class ClxDerived : public ClxBase
{
public:
ClxDerived() {};
~ClxDerived() { cout << "Do derived class destruct!" << endl; };
};
int main()
{
ClxBase *pTest = new ClxDerived;
ClxDerived derived;
delete pTest;
}
另一個(gè)例子輸出的卻是 :
Do base class destruct
Do derived class destruct!
Do base class destruct
說明了兩個(gè)問題，只想派生類對象的基類指針需要基類聲明虛系構(gòu)函數(shù)才能調(diào)用派生類指針，而派生類對象卻不用基類聲明虛系構(gòu)函數(shù)就能調(diào)用派生類指針