#ifndef EMPLOYEE_HPP
#define EMPLOYEE_HPP 
#include<iostream>
#include<math.h>
using namespace std;

class Complex
{
	public:
		~Complex();
		Complex(float a1)
		{
			a=a1;
			b=0;
		}
		Complex(float a1,float b1)
		{
			a=a1;
			b=b1;
		}
		Complex(const Complex &c)
		{
			a=c.a;
			b=c.b;
		}
		float get_real()const
		{
			return a;
		}
		float get_imag()const
		{
			return b;
		}
		void show()const
		{
			if(b>=0)
			printf("%.2f+%.2fi\n",a,b);
			else
			printf("%.2f-%.2fi\n",a,b*(-1)); 
		}
		void add(Complex c2)
		{
			a+=c2.a;
			b+=c2.b;
		}
		friend Complex add(Complex c1,Complex c2)
		{
			Complex c(0,0);
			c.a=c1.a+c2.a;
			c.b=c1.b+c2.b;
			return c;
		}
		friend bool is_equal(Complex c1,Complex c2)
		{
			if(c1.a==c2.a&&c1.b==c2.b)
			return 1;
			else
			return 0;
		}
		friend float abs(Complex &c)
		{
			return sqrt(c.a*c.a+c.b*c.b);
		}
	private:
		float a;
		float b; 
};
Complex::~Complex()
{
	
}
#endif 

　　Complex.h標頭檔案

#include "Complex.h"
#include<iostream>
int main()
{
	using namespace std;
	Complex c1(3,4);
	const Complex c2(4.5);
	Complex c3(c1);
	
	cout<<"c1=";
	c1.show();
	cout<<endl;
	
	cout<<"c2=";
	c2.show();
	cout<<endl;
	cout<<"c2.imag="<<c2.get_imag()<<endl;
	
	cout<<"c3=";
	c3.show();
	cout<<endl;
	
	cout<<"abs(c1)=";
	cout<<abs(c1)<<endl;
	
	cout<<boolalpha;
	cout<<"c1==c3:"<<is_equal(c1,c3)<<endl;
	cout<<"c1==c2:"<<is_equal(c1,c2)<<endl;
	
	Complex c4(0,0);
	c4=add(c1,c2);
	cout<<"c4=c1+c2=";
	c4.show();
	cout<<endl;
	
	c1.add(c2);
	cout<<"c1+=c2,"<<"c1=";
	c1.show();
	cout<<endl;
}

　　task3.cpp

執行結果為：

標頭檔案USER,h

#ifndef USER_HPP
#define USER_HEPP
#include<iostream>
#include<iomanip>
#include<string>
using namespace std;
class User
{
	private:
		string name;
		string password;
		string email;
		static int count;//設定靜態成員 
	public:
		~User();
		User(string n1);
		User(string n1,string p1,string e1);
		void set_email();
		void change_password();
		void print_info();
		void print_n();
		static void display_count();
}; 
int User::count=0;//靜態成員初始化 
User::~User()
{
	++count;
}
User::User(string n1)
{
	name=n1;
	password="111111";
	email="\0";
	++count;
}
User::User(string n1,string p1,string e1)
{
	name=n1;
	password=p1;
	email=e1;
	++count;
}
void User::set_email()
{
	string newemail;
	bool flag=0; 
	cout<<"Please set your e-mail:";
	cin>>newemail;
	do
	{
		int i=0;
		flag=0;
		for(i=0;i<newemail.size();i++)
		{
			if(newemail[i]=='@')
			flag=1; 
		}
		if(flag)
		{
			email=newemail;
			break;
		}
		else
		{
			cout<<"E-mail adress is illegal"<<endl;
		}
		cout<<"Please set your e-mail:";
		cin>>newemail;
	}
	while(!flag);
}
void User::change_password()
{
	string oldpassword;
	int num=0;
	bool flag=0;
	do
	{
		cout<<"Enter old password:";
		cin>>oldpassword;
		if(oldpassword.size()!=6)
		{
			cout<<"password length error"<<endl;
			flag=0;
		}
		num++;
	}
	while(oldpassword!=password&&count!=3&&!flag);//密碼不滿3次繼續進行
	if(count==3)
	{
		cout<<"Set new password error\n";
		exit(0);
	}
	else
	{
		string newpassword;
		cout<<"Please set new password:";
		cin>>newpassword;
		while(newpassword.size()!=6)
		{
			cout<<"password length error\n";
			cout<<"Please set new password:";
			cin>>newpassword;
		} 
		password=newpassword;
	}
}
void User::print_info()
{
	cout<<"NAME:"<<name<<endl;
	cout<<"PASSWORD:******"<<endl;
	cout<<"E-MAIL:"<<email<<endl; 
}
void User::print_n()
{
	cout<<"There are "<<count<<" users"<<endl;
}
#endif 

　　task4.cpp

#include "USER.h"
#include <iostream>
int main()
{
  using namespace std;

    cout << "testing 1......" << endl;
    User user1("Jonny", "92197", "[email protected]");
    user1.print_info();

    cout << endl
         << "testing 2......" << endl
         << endl;
    User user2("Leonard");
    user2.change_password();
    user2.set_email();
    user2.print_info();

    user2.print_n();
}

　　執行測試截圖為：