第三周 类和对象提高 - PKU[课程作业]程序设计与算法（三）C++面向对象程序设计

1:返回什么才好呢

#include <iostream>
using namespace std;
class A {
public:
	int val;

	A(int n = 123)
	{
		val = n;
	} 
	A & GetObj()
	{
		return *this;
	}
};
int main()
{
	int m,n;
	A a;
	cout << a.val << endl;
	while(cin >> m >> n) {
		a.GetObj() = m;
		cout << a.val << endl;
		a.GetObj() = A(n);
		cout << a.val<< endl;
	}
	return 0;
}

2:Big & Base 封闭类问题

#include <iostream>
#include <string>
using namespace std;
class Base {
public:
	int k;
	Base(int n):k(n) { }
};
class Big
{
public:
	int v;
	Base b;
	Big(int n):b(n) { v = n; }
};
int main()
{
	int n;
	while(cin >>n) {
		Big a1(n);
		Big a2 = a1;
		cout << a1.v << "," << a1.b.k << endl;
		cout << a2.v << "," << a2.b.k << endl;
	}
}

3:编程填空：统计动物数量

/* 见：静态成员示例，继承和多态 */
#include <iostream>
using namespace std;

class Animal{
	protected:
		static int number;
	public:
		Animal() {}
		virtual ~Animal() {}
	friend void print();
}; 
int Animal::number = 0;

class Dog: public Animal{
	private:
		static int number;
	public:
		Dog() {
			Animal::number++;
			number++;
		}
		~Dog() {
			Animal::number--;
			number--; 
		}
	friend void print();
};
int Dog::number = 0;

class Cat: public Animal{
	private:
		static int number;
	public:
		Cat() {
			Animal::number++;
			number++;
		}
		~Cat() {
			Animal::number--;
			number--;
		}
	friend void print();
};
int Cat::number = 0;

void print() {
	cout << Animal::number << " animals in the zoo, " << Dog::number << " of them are dogs, " << Cat::number << " of them are cats" << endl;
}

int main() {
	print();
	Dog d1, d2;
	Cat c1;
	print();
	Dog* d3 = new Dog();
	Animal* c2 = new Cat;
	Cat* c3 = new Cat;
	print();
	delete c3;
	delete c2;
	delete d3;
	print();
}

4:这个指针哪来的

#include <iostream>
using namespace std;

struct A
{
	int v;
	A(int vv):v(vv) { }
	const A *getPointer() const
	{
		return this;
	}
};

int main()
{
	const A a(10);
	const A * p = a.getPointer();
	cout << p->v << endl;
	return 0;
}

5:魔兽世界之一：备战

魔兽世界专门的文章，如下

https://blog.csdn.net/MoMo_flamboyant/article/details/79955977