练习.txt

钱能主编 C++程序设计教程（第一版） 该书习题的答案代码

15.1
#include <iostream.h>

class Plant
{
public:
	Plant(int a=10)
	{
		cout<<"in constructing"<<endl;
		priV=a;
		pubV++;
		cout<<"pubV:"<<pubV<<endl;
	}
	void Display();
	static void Dis_sta();
	~Plant()
	{
		cout<<"destruct class "<<priV<<endl;
		cout<<"befoer destruction,pubV:"<<pubV<<endl;
		pubV--;
		cout<<"after destruction,pubV:"<<pubV<<endl;
	}
protected:
	int priV;
	static int pubV;
};
int Plant::pubV = 0;

void Plant::Dis_sta()
{
	cout<<pubV<<endl;
}

void Plant::Display()
{
	cout<<"priV:"<<priV<<endl;
}

void main()
{
	Plant c1(5);
	c1.Display();
	cout<<"----------------------"<<endl;

	Plant c2;
	c2.Display();
	cout<<"----------------------"<<endl;

	Plant c3(15);
	c3.Display();
	cout<<"----------------------"<<endl;
}

15.2
#include <iostream.h>

class Animal
{
public:
	void SetValue(int);
	void SetValue(int,int);
protected:
	int itsWeight;
	int itsAge;
};

void Animal::SetValue(int tw)
{
	itsWeight=tw;
	cout<<"weight:"<<itsWeight<<endl;
}
void Animal::SetValue(int tw,int tn)
{
	itsWeight=tw;
	itsAge=tn;
	cout<<"weight:"<<itsWeight<<","
		<<"age:"<<itsAge<<endl;
}

void main()
{
	Animal peppy;
	peppy.SetValue(5);
	peppy.SetValue(7,9);
}

15.3
#include <iostream.h>
#include <math.h>

class Boat;

class Car
{
public:
	Car(int j) {size=j;}
	float Leisure(int time)
	{
		return float(sqrt(time))*size;
	}
	int get()
	{
		return size;
	}
protected:
	int size;
};

class Boat
{
public:
	Boat(int j) {size=j;};
	float Leisure(int time)
	{
		return float(sqrt(time))*size;
	}
	int get()
	{
		return size;
	}
protected:
	int size;
};

void main()
{
	Car c1(2);
	Boat b1(3);
	int time=22;
	cout<<c1.Leisure(time)*b1.Leisure(time)<<endl;
}