第三章

2

#include <iostream> using namespace std; class Date {public:  Date(int,int,int); Date(int,int); Date(int); Date();  void display(); private: int month; int day; int year; }; Date::Date(int m,int d,int y):month(m),day(d),year(y) { } Date::Date(int m,int d):month(m),day(d) {year=2005;} Date::Date(int m):month(m) {day=1;  year=2005; } Date::Date() {month=1; day=1; year=2005; } 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; }

3

#include <iostream> 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; } 

4

#include <iostream> using namespace std; class Student {public:  Student(int n,float s):num(n),score(s){} void display(); private: int num; float score; }; void Student::display()  {cout<<num<<" "<<score<<endl;} int main()  {Student stud[5]={  Student(101,78.5),Student(102,85.5),Student(103,98.5), Student(104,100.0),Student(105,95.5)}; Student *p=stud;  for(int i=0;i<=2;p=p+2,i++) p->display(); return 0; }

5

#include <iostream> using namespace std; class Student {public:  Student(int n,float s):num(n),score(s){} int num; float score; }; void main()  {Student stud[5]={  Student(101,78.5),Student(102,85.5),Student(103,98.5), Student(104,100.0),Student(105,95.5)}; void max(Student* ); Student *p=&stud[0]; max(p); } void max(Student *arr)  {float max_score=arr[0].score; int k=0;  for(int i=1;i<5;i++)  if(arr[i].score>max_score) {max_score=arr[i].score;k=i;} cout<<arr[k].num<<" "<<max_score<<endl; } 

6

#include <iostream> 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; } 

7

#include <iostream> 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() {const Student stud(101,78.5); stud.display();stud.change(101,80.5); stud.display(); return 0; } 

8

#include <iostream> 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(); } 

9

#include <iostream> 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=0.98*rate;  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; 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; } 

10

#include <iostream> 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 month; int day; int year; }; Date::Date(int m,int d,int y) {month=m; day=d; year=y; } void display(const Date &d,const Time &t) {  cout<<d.month<<"/"<<d.day<<"/"<<d.year<<endl; cout<<t.hour<<":"<<t.minute<<":"<<t.sec<<endl; } int main() {  Time t1(10,13,56); Date d1(12,25,2004); display(d1,t1); return 0; } 

11

#include <iostream> using namespace std; class Time; class Date {public:  Date(int,int,int); friend Time; private:  int month; int day; int year; }; Date::Date(int m,int d,int y):month(m),day(d),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.month<<"/"<<d.day<<"/"<<d.year<<endl;  cout<<hour<<":"<<minute<<":"<<sec<<endl; } int main() {  Time t1(10,13,56); Date d1(12,25,2004); t1.display(d1); return 0; } 

12

#include <iostream> 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<<endl; Compare<float> cmp2(45.78,93.6);  cout<<cmp2.max()<<" is the Maximum of two float numbers."<<endl; cout<<cmp2.min()<<" is the Minimum of two float numbers."<<endl<<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; return 0; }