#include <iostream>
using namespace std;
class A
{
public:
A();
~A();
};
A::A()
{
cout<<"A star"<<endl;
}
A::~A()
{
cout<<"Delete class AP/n"<<endl;
}
class B : public A
{
public:
B();
~B();
};
B::B()
{
cout<<"B star"<<endl;
}
B::~B()
{
cout<<"Delete class BP/n"<<endl;
}
int main(int argc, char* argv[])
{
A *a = new B;
delete a;
//A *b=new B;
//delete b;
return 0;
}
A star
B star
Delete class AP/n
因此,在创建子类对象时,为了初始化从父类继承来的数据成员,系统需要调用其父类的构造方法。
这个时候需要加一个 virtual ~A()
A star
B star
Delete class BP/n
Delete class AP/n
需要注意的是 要有delete 不然析构函数不会被调用
a virtual function or virtual method is a function or method whose behavior can be overridden within an inheriting class by a function with the same signature. This concept is a very important part of the polymorphism portion of object-oriented programming (OOP).
"A pure virtual function or pure virtual method is a virtual function that is required to be implemented by a derived class that is not abstract" - Wikipedia
So, the virtual function can be overriden and the pure virtual must be implemented.
//============================================================================
// Name : test.cpp
// Author :
// Version :
// Copyright : Your copyright notice
// Description : Hello World in C++, Ansi-style
//============================================================================
#include <iostream>
using namespace std;
class A
{
public:
A();
virtual ~A();
};
A::A()
{
cout<<"A star"<<endl;
}
A::~A()
{
cout<<"Delete class AP/n"<<endl;
}
class B : public A
{
public:
B();
~B();
};
B::B()
{
cout<<"B star"<<endl;
}
B::~B()
{
cout<<"Delete class BP/n"<<endl;
}
int main(int argc, char* argv[])
{
B *a = new B;
delete a;
//A *b=new B;
//delete b;
return 0;
}
A star
B star
Delete class BP/n
Delete class AP/n
原文链接: https://www.cnblogs.com/leetcode/p/3192594.html
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