c++第三章作业

浅浅的花香味﹌ 2022-08-07 16:41 279阅读 0赞

**C ++ 第三章作业**

**1、答案：**

**构造函数的作用**：用于新建对象的初始化工作。  
  **析构函数的作用**：用于在撤销对象前，完成一些清理工作，比如：释放内存等。  
  每当创建对象时，需要添加初始化代码时，则需要定义自己的构造函数；

而对象撤销时，需要自己添加清理工作的代码时，则需要定义自己的析构函数。

**2**.略。

**3.\#include <iostream>//第三小题  
using namespace std;  
class Date  
\{  
public:  
Date(int=1,int=1,int=2005);  
void display();  
private:  
int month;  
int day;  
int year;  
\};  
Date::Date(int m,int d,int y):month(m),day(d),year(y)\{\}  
void Date::display()  
\{  
 cout<<month<<"/"<<day<<"/"<<year<<endl;  
\}  
int main()  
\{  
 Date d1(10,13,2005);  
 Date d2(12,30);  
 Date d3(10);  
 Date d4;  
 d1.display();  
 d2.display();  
 d3.display();  
 d4.display();  
 return 0;  
\}  
  
  
![Center][]**

**4.\#include <iostream>//第四小题  
using namespace std;  
class Student  
\{  
public:  
Student(int n,int s):num(n),score(s)\{\}  
void display();  
private:  
int num;  
int score;  
\};  
void Student::display()  
\{  
 cout<<num<<" "<<score<<endl;  
\}  
int main()  
\{  
Student stud\[5\]=\{Student(1,88),Student(2,86),Student(3,90),Student(4,78),Student(5,88)\};  
Student \*p=stud;  
for(int i=0;i<3;p+=2,i++)  
p->display();  
 return 0;  
\}**

**![Center 1][]**

**5.\#include<iostream>//第三章第五小题   
using namespace std;  
class Student \{  
public:  
Student(int n,int s):num(n),score(s)\{\};  
  
  
  
int num;  
int score;  
\};  
void stu\_max(Student \*p)\{  
int i=0,k=0,max=p\[0\].score;  
for(i;i<5;i++)\{  
if(p\[i\].score>max)  
\{  
max=p\[i\].score;k++;\}  
  
\}  
  
cout<<"最高分"<<p\[k\].score<<"学号"<<p\[k\].num;   
\}  
  
  
  
  
int main()\{  
  
Student std\[5\]=\{Student(1,88),Student  
  
  
(2,86),Student  
  
  
(3,90),Student(4,78),Student(5,88)\};  
Student \*p=std;  
stu\_max(p);  
return 0;  
  
\}![Center 2][]**

**6.\#include <iostream>//第六小题  
using namespace std;  
class Student  
\{  
public:  
Student(int n,float s):num(n),score(s)\{\}  
void change(int n,float s)  
\{  
num=n;  
score=s;  
\}  
void display()  
\{  
cout<<num<<" "<<score<<endl;  
\}  
private:  
int num;  
float score;  
\};  
int main()  
\{  
 Student stud(101,78.5);  
 stud.display();  
 stud.change(101,80.5);  
 stud.display();  
 return 0；  
｝  
  
  
![Center 3][]**

**7.（1） \#include <iostream>//7.(1)小题  
using namespace std;  
class Student  
\{  
public:  
Student(int n,float s):num(n),score(s)\{\}  
void change(int n,float s)  
\{  
num=n;  
score=s;  
\}  
//void display()  
void display()const  
\{  
cout<<num<<" "<<score<<endl;  
\}  
private:  
int num;  
float score;  
\};  
int main()  
\{  
   
 const Student stud(101,78.5);  
 stud.display();  
   
 return 0;  
\}![Center 4][]**

**7.（2） \#include <iostream>//7.(2)小题  
using namespace std;  
class Student  
\{  
public:  
Student(int n,float s):num(n),score(s)\{\}  
//void change(int n,float s)  
void change(int n,float s)const  
\{  
num=n;  
score=s;  
\}  
//void display()  
void display()const  
\{  
cout<<num<<" "<<score<<endl;  
\}  
private:  
//int num;  
mutable int num;//将变量变为可改变的值  
//float score;  
mutable float score;  
\};  
int main()  
\{  
 //Student stud(101,78.5);  
 const Student stud(101,78.5);  
 stud.display();  
 stud.change(101,80.5);  
 stud.display();  
 return 0;  
\}**

**![Center 5][]**

**7.（3）\#include <iostream>//7.(3)小题  
using namespace std;  
class Student  
\{  
public:  
Student(int n,float s):num(n),score(s)\{\}  
void change(int n,float s)  
\{  
num=n;  
score=s;  
\}  
void display()  
\{  
cout<<num<<" "<<score<<endl;  
\}  
private:  
int num;  
float score;  
\};  
int main()  
\{  
 Student stud(101,78.5);  
 Student \*p=&stud;  
 p->display();  
 p->change(101,80.5);  
 p->display();  
 return 0;  
\}  
![Center 6][]**

**7.（4） \#include <iostream>//7.(4)小题  
using namespace std;  
class Student  
\{  
public:  
Student(int n,float s):num(n),score(s)\{\}  
//void change(int n,float s)  
void change(int n,float s)const  
\{  
num=n;  
score=s;  
\}  
//void display()  
void display()const  
\{  
cout<<num<<" "<<score<<endl;  
\}  
private:  
//int num;  
mutable int num;  
//float score;  
mutable float score;  
\};  
int main()  
\{  
 //Student stud(101,78.5);  
 const Student stud(101,78.5);  
 stud.display();  
 const Student \*p = &stud;  
 //stud.change(101,80.5);  
 p->change(101,80.5);  
 //stud.display();  
 p->display();  
 return 0;  
\}![Center 7][]**

**7.（5）\#include <iostream>//7.(5)小题  
using namespace std;  
class Student  
\{  
public:  
Student(int n,float s):num(n),score(s)\{\}  
//void change(int n,float s)  
void change(int n,float s)const  
\{  
num=n;  
score=s;  
\}  
//void display()  
void display()const  
\{  
cout<<num<<" "<<score<<endl;  
\}  
private:  
//int num;  
mutable int num;  
//float score;  
mutable float score;  
\};  
int main()  
\{  
 //Student stud(101,78.5);  
 const Student stud(101,78.5);  
 stud.display();  
 const Student \*p = &stud;  
 //stud.change(101,80.5);  
 p->change(101,80.5);  
 //stud.display();  
 p->display();  
 return 0;  
\}**

![Center 8][]

**8、\#include <iostream>//第八小题  
using namespace std;  
class Student  
\{  
public:  
Student(int n,float s):num(n),score(s)\{\}  
void change(int n,float s)  
\{  
num=n;  
score=s;  
\}  
void display()  
\{  
cout<<num<<" "<<score<<endl;  
\}  
private:  
int num;  
float score;  
\};  
int main()  
\{  
 Student stud(101,78.5);  
 void fun(Student &);  
 fun(stud);  
 return 0;  
\}  
void fun(Student &stu)  
\{  
 stu.display();  
 stu.change(101,80.5);  
 stu.display();  
\}**

**![Center 9][]**

**9、\#include <iostream>//第九小题  
using namespace std;  
class Product  
\{  
public:  
Product(int n,int q,float p):num(n),quantity(q),price(p)\{\}  
void total();  
static float average();  
static void display();  
private:  
int num;  
int quantity;  
float price;  
static float discount;  
static float sum;  
static int n;  
\};  
void Product::total()  
\{  
 float rate=1.0;  
 if(quantity>10)  
rate=rate\*0.98;  
 sum=sum+quantity\*price\*rate\*(1-discount);  
 n=n+quantity;  
\}  
void Product::display()  
\{  
 cout<<sum<<endl;  
 cout<<average()<<endl;  
\}  
float Product::average()  
\{  
 return (sum/n);  
\}  
float Product::discount=0.05;  
float Product::sum=0.0;  
int Product::n=0;  
int main()  
\{  
Product prod\[3\]=\{Product(101,5,23.5),Product  
  
  
(102,12,24.56),Product(103,100,21.5)\};  
for(int i=0;i<3;i++)  
prod\[i\].total();  
Product::display();  
return 0;  
\}**

**![Center 10][]**

**10、\#include <iostream>//第十小题  
using namespace std;  
class Date;  
class Time  
\{  
public:  
Time(int ,int ,int );  
friend void display(const Date &,const Time &);  
private:  
int hour;  
int minute;  
int sec;  
\};  
Time::Time(int h,int m,int s)  
\{  
 hour=h;  
 minute=m;  
 sec=s;  
\}  
class Date  
\{  
public:  
Date(int ,int ,int );  
friend void display(const Date &,const Time &);  
private:  
int day;  
int month;  
int year;  
\};  
Date::Date(int d,int m,int y)  
\{  
 day=d;  
 month=m;  
 year=y;  
\}  
void display(const Date &d,const Time &t)  
\{  
 cout<<d.day<<" "<<d.month<<" "<<d.year<<endl;  
 cout<<t.hour<<" "<<t.minute<<" "<<t.sec<<endl;  
\}  
int main()  
\{  
 Time t(10,13,56);  
 Date d(10,25,2004);  
 display(d,t);  
 return 0;  
\}  
![Center 11][]**

**11、\#include <iostream>//第十 一小题  
using namespace std;  
class Time;  
class Date  
\{  
public:  
Date(int ,int ,int);  
friend Time;  
private:  
int day;  
int month;  
int year;  
\};  
Date::Date(int d,int m,int y)  
\{  
 int day=d;  
 int month=m;  
 int year=y;  
\}  
class Time  
\{  
public:  
Time(int,int,int);  
void display(const Date &);  
private:  
int hour;  
int minute;  
int sec;  
\};  
Time::Time(int h,int m,int s)  
\{  
 hour=h;  
 minute=m;  
 sec=s;  
\}  
void Time::display(const Date &d)  
\{  
 cout<<d.day<<" "<<d.month<<" "<<d.year<<endl;  
 cout<<hour<<" "<<minute<<" "<<sec<<endl;  
\}  
int main()  
\{  
 Time t(10,13,56);  
 Date d(12,25,2004);  
 t.display(d);  
 return 0;  
\}**

**![Center 12][]**

**12、  
  
\#include <iostream>//第十二小题  
using namespace std;  
template<class numtype>  
class Compare  
\{  
 public:  
Compare(numtype a,numtype b);  
numtype max();  
numtype min();  
 private:  
numtype x,y;  
\};  
template<class numtype>  
Compare<numtype>::Compare(numtype a,numtype b)  
\{  
 x=a;  
 y=b;  
\}  
template<class numtype>  
numtype Compare<numtype>::max()  
\{  
return (x>y)?x:y;  
\}  
template<class numtype>  
numtype Compare<numtype>::min()  
\{  
    return (x<y)?x:y;  
\}  
int main()  
\{  
Compare<int> cmp1(3,7);  
cout<<cmp1.max()<<"is the Maximum of two integer numbers."<<endl;  
cout<<cmp1.min()<<"is the Minimum of two integer numbers."<<endl;  
Compare<float> cmp2(45.78,93.6);  
cout<<cmp2.max()<<"is the Maximum of two integer numbers."<<endl;  
cout<<cmp2.min()<<"is the Minimum of two integer numbers."<<endl;  
Compare<char> cmp3('a','A');  
cout<<cmp3.max()<<"is the Maximum of two characters."<<endl;  
cout<<cmp3.min()<<"is the Minimum of two characters."<<endl;  
  
  
\}  
  
![Center 13][]**

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