#include<iostream>
#include<cmath>
using namespace std;
class Complex
{
public:
    Complex(int r=0,int i=0):real((double)r),imag((double)i){}
    Complex(double r);
    Complex(double r, double i);
    ~Complex()=default;
    Complex(const Complex &a)//复制构造函数
    {
        real=a.real;
        imag=a.imag;
    }
    double get_real() const//返回函数实部
    {
        return real;
    }
    double get_imag() const//返回函数虚部
    {
        return imag;
    }
    void show() const//输出复数
    {
        if (get_imag()>0)
            cout<<get_real()<<"+"<<get_imag()<<"i"<<endl;
        else if (get_imag()==0)
            cout<<get_real()<<endl;
        else
            cout<<get_real()<<"-"<<-get_imag()<<"i"<<endl;
    }
    void add(const Complex &a)//用于把一个复数加到自身
    {
        real+=a.real;
        imag+=a.imag;
    }
    friend Complex add(const Complex &a1, const Complex &a2);//友元函数：实现两个复数相加
    friend bool is_equal(const Complex &a1, const Complex &a2);//友元函数，判断相等
    friend double abs(const Complex &a);//友元函数，对复数进行取模运算
private:
    double real;
    double imag;
};
Complex::Complex(double r)
{
    real=r;
    imag=0;
}
Complex::Complex(double r, double i)
{
    real=r;
    imag=i;
}

Complex add(const Complex &a1, const Complex &a2)
{
    Complex a3;
    a3.real=a1.real+a2.real;
    a3.imag=a1.imag+a2.imag;
    return a3;
}

bool is_equal(const Complex &a1, const Complex &a2)
{
    if ((a1.real==a2.real)&&(a1.imag==a2.imag))
        return true;
    else
        return false;
}

double abs(const Complex &a)
{
    double sum;
    sum=sqrt(a.real*a.real+a.imag*a.imag);
    return sum;
}

#include"Complex.hpp" 
#include<iostream>
int main()
{
    using namespace std;
    
    Complex c1(7,-1);
    const Complex c2(-2,4);
    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<<boolalpha;
    cout<<"c1==c3:"<<is_equal(c1,c3)<<endl;
    cout<<"c1==c2:"<<is_equal(c1,c2)<<endl;
    
    Complex c4;
    c4=add(c1,c2);
    cout<<"c4=c1+c2=";
    c4.show();
    cout<<endl;
    
    c1.add(c2);
    cout<<"c1+=c2,"<<"c1=";
    c1.show();
    cout<<endl;
}

 

#include <iostream>
#include <string>
using namespace std;

class User
{
private:
    string name;
    string password;
    string email;
    static int n;
public:
    User(string name1);
    User(string nameq,string password1,string email1);
    ~User()=default;
    void set_email()
    {
        string h;
        cout<<"Enter email address:";
        cin>>h;
        email=h;
        cout<<"email is set successfully"<<endl;
    }
    void change_passwd()
    {
        string p,newp;
        cout<<"Enter old password:";
        int t=0;
        for(int i=1;i<=3;i++)
        {
            cin>>p;
            if(p!=password)
            {
                t++;
                if(t==3)
                {
                    cout<<"password input error.Please try after a while."<<endl;
                    break;
                }
                else
                    cout<<"password input error. Please re-enter again:";
            }
            else
            {
                cout<<"Enter new password:";
                cin>>p;
                cout<<"new password is set successfully..."<<endl;
                break;
            }
        }
    }
    void print_info()
    {
        cout<<"name:"<<name<<endl;
        cout<<"password:******"<<endl;
        cout<<"email:"<<email<<endl;
    }
    static void print_n()
    {
        cout<<"there are "<<n<<" users."<<endl;
    }
};
int User::n=0;
User::User(string name1)
{
    name=name1;
    password="111111";
    email=" ";
    n++;
}
User::User(string name1,string password1,string email1)
{
    name=name1;
    password=password1;
    email=email1;
    n++;
}

#include "User.hpp"
#include <iostream>

int main()
{
    using namespace std;

    cout << "testing 1......" << endl;
    User user1("Jonny", "92197", "xyz@hotmail.com");
    user1.print_info();

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

    User::print_n();
}