1:返回什麼才好呢

程式填空，使其按要求輸出

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

	A(int

// 在此處補充你的程式碼

};
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;
}
 

輸入

多組資料，每組一行，是整數 m 和 n

輸出

先輸出一行：  123  然後，對每組資料，輸出兩行，第一行是m,第二行是n

樣例輸入

2 3
4 5

樣例輸出

123
2
3
4
5 

答案：

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

	A(int
n)
	{
	    val=n;
	}
    A()
	{
	    val=123;
	}
	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 封閉類問題

程式填空，輸出指定結果

#include <iostream>
#include <string>
using namespace std;
class Base {
public:
	int k;
	Base(int n):k(n) { }
};
class Big
{
public:
	int v;
	Base b;

// 在此處補充你的程式碼

};
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;
	}
}
 

輸入

多組資料，每組一行，是一個整數

輸出

對每組資料，輸出兩行，每行把輸入的整數列印兩遍

樣例輸入

3
4

樣例輸出

3,3
3,3
4,4
4,4	

答案：

#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:程式設計填空：統計動物數量

程式碼填空，使得程式能夠自動統計當前各種動物的數量

#include <iostream>
using namespace std;

// 在此處補充你的程式碼

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();
}

輸入

無

輸出

0 animals in the zoo, 0 of them are dogs, 0 of them are cats 3 animals in the zoo, 2 of them are dogs, 1 of them are cats 6 animals in the zoo, 3 of them are dogs, 3 of them are cats 3 animals in the zoo, 2 of them are dogs, 1 of them are cats

答案：

#include <iostream>
using namespace std;
class Animal
{
public:
    static int number;
    Animal()
    {
        number++;
    }
    virtual ~ Animal()
    {
        number--;
    }
};
class Dog:public Animal
{
public:
    static int number;
    Dog()
    {
        number++;
    }
    ~Dog()
    {
        number--;
    }
};
class Cat:public Animal
{
public:
    static int number;
    Cat()
    {
        number++;
    }
    ~Cat()
    {
        number--;
    }
};
int Animal::number = 0;
int Cat::number = 0;
int Dog::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:這個指標哪來的

填空，按要求輸出

#include <iostream>
using namespace std;

struct A
{
	int v;
	A(int vv):v(vv) { }

// 在此處補充你的程式碼

};

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

輸入

無

輸出

10

答案：

#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;
}