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c++ code：（12）polymorphism

news 来源：原创 2024/5/20 19:16:27

多态执行顺序是有讲究滴。。。。。。。

/*9593

程序填空产生指定输出 
 
样例输入：
无
样例输出

D::Fun
B::Fun
D::Fun
nBVal=2
nBVal=24
nDVal=8
B::Fun
nBVal=12
 
*/

#include <iostream>
using namespace std;
class B { 
	private: 
		int nBVal; 
	public: 
		void Print() 
		{ cout << "nBVal="<< nBVal << endl; } 
		void Fun() 
		{cout << "B::Fun" << endl; } 
		B ( int n ) { nBVal = n;} 
}; 
//your code starts here
class D :public B { 
	private : 
		int nDVal; 
	public: 
		void Print() { 
			B::Print(); 
			cout << "nDVal="<<nDVal<<endl; 
		} 
		D( int n) : B(3*n) 
		{ nDVal = n; } 
		void Fun() 
		{ cout << "D::Fun" << endl; } 
}; 
//your codes ends here
int main() { 
	B * pb; D * pd; 
	D d(4); d.Fun(); 
	pb = new B(2); pd = new D(8); 
	pb -> Fun(); pd->Fun(); 
	pb->Print (); pd->Print (); 
	pb = & d; pb->Fun(); 
	pb->Print(); 
	return 0;
}

/*9594
程序填空输出指定结果
	
输出：
A::Fun 
C::Do 

*/
#include <iostream> 
using namespace std;
class A { 
	private: 
	int nVal; 
	public: 
	void Fun() 
	{ cout << "A::Fun" << endl; }; 
	void Do() 
	{ cout << "A::Do" << endl; } 
}; 
class B:public A { 
	public: 
	virtual void Do() 
	{ cout << "B::Do" << endl;} 
}; 
class C:public B { 
	public: 
	void Do( ) 
	{ cout <<"C::Do"<<endl; } 
	void Fun() 
	{ cout << "C::Fun" << endl; } 
}; 
void Call( 
//your code starts here
B & p
//your code ends here  
) { 
	p.Fun(); p.Do(); 
} 
int main() { 
	C c; 
	Call( c); 
	return 0;
}

/*
程序填空输出指定结果

destructor B
destructor A

*/

 
#include <iostream> 
using namespace std;
class A 
{ 
public:
	A() { }
//your code starts here	
	virtual ~A() { cout << "destructor A" << endl; } 
//your code ends here	
}; 
class B:public A { 
	public: 
	~B() { cout << "destructor B" << endl; } 
}; 
int main() 
{ 
	A * pa; 
	pa = new B; 
	delete pa; 
	return 0;
}

/*

程序填空，输出：
 
A::Fun
A::Do
A::Fun
C::Do

*/
#include <iostream>
using namespace std;
class A {
	private:
	int nVal;
	public:
	void Fun()
	{ cout << "A::Fun" << endl; };
	virtual void Do()
	{ cout << "A::Do" << endl; }
};
class B:public A {
	public:
	virtual void Do()
	{ cout << "B::Do" << endl;}
};
class C:public B {
	public:
	void Do( )
	{ cout <<"C::Do"<<endl; }
	void Fun()
	{ cout << "C::Fun" << endl; }
};
void Call(
//your code starts here
A* p
//your code ends here
) {
	p->Fun(); p->Do();
}
int main() {
	Call( new A());
	Call( new C());
	return 0;
}