1.析构函数是可以显式调用的。
2.new也可以用来动态开辟有虚函数的类。
class Foo
{
public:
virtual ~Foo() {cout<<"the destructor of Foo"<<endl;}
virtual void display() const { cout<<"display class Foo"<<endl; }
private:
int x_;
};
class Child: public Foo
{
public:
virtual ~Child() {cout<<"the destructor of Child"<<endl;}
void display() const {cout<<"display class Child"<<endl;}
private:
int y_;
};
int main()
{
cout<<sizeof(Foo)<<endl; //8
cout<<sizeof(Child)<<endl; //12
cout<<endl;
Foo* fp = new Foo;
fp->display(); // display class Foo
cout<<sizeof(*fp)<<endl; // 8
fp->~Foo(); // the destructor of Foo
cout<<endl;
Foo* fc = new Child;
fc->display(); // display class Child
cout<<sizeof(*fc)<<endl; // 8!!! 因为fc为Foo类型的指针，所以解引用出来的大小为Foo类的大小
fc->~Foo(); // the destructor of Child, the destructor of Foo
cout<<endl;
Child* fcc = new Child;
fcc->display(); // display class Child
cout<<sizeof(*fcc)<<endl; // 12
fcc->~Child(); // the destructor of Child, the destructor of Foo
cout<<endl;
delete fp; // 调用析构函数。。。。。。
delete fc;
delete fcc;
fp = fc = fcc = NULL;
}