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# 实验2

```头文件：
#pragma once
#include<iostream>
#include<math.h>
using namespace std;

class Complex
{
public:
Complex() :real{ 0 }, imag{ 0 }{}
~Complex() {}
Complex(double real) :real{ real }, imag{ 0 }{}
Complex(double real, double imag) :real{ real }, imag{ imag }{}
Complex(const Complex& other) :real{ other.real }, imag{ other.imag }{}

double get_real() const { return real; };
double get_imag() const { return imag; };
void show() const;

friend Complex add(Complex c1, Complex c2);
friend bool is_equal(Complex c1, Complex c2);
friend double abs(Complex& other);

private:
double real, imag;
};

void Complex::show() const
{
if (real != 0)
{
cout << real;
if (imag != 0 && imag > 0)
{
cout << "+" << imag << "i";
}
else if (imag != 0 && imag < 0)
{
cout << imag << "i";
}
}
else
{
if (imag != 0)
cout << imag << "i";
else
cout << "0";
}
}

{
real += other.real;
imag += other.imag;
}

Complex add (Complex c1, Complex c2)
{
Complex c3;
c3.real = c1.real + c2.real;
c3.imag = c1.imag + c2.imag;
return c3;
}

bool is_equal(Complex c1, Complex c2)
{
if (c1.real == c2.real && c1.imag == c2.imag)
return true;
else
return false;
}

double abs(Complex& other)
{
double t;
t = (double)sqrt((double)pow(other.real, 2) + (double)pow(other.imag, 2));
return t;
}

#include <iostream>
#include "Complex.h"

void test() {
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;
cout << "c4 = c1 + c2 = ";
c4.show();
cout << endl;
cout << "c1 += c2, " << "c1 = ";
c1.show();
cout << endl;
}
int main() {
test();
}```

```头文件
#pragma once
#include<iostream>
#include<string>
using namespace std;
class User
{
public:
User(string n1, string p1 = "111111", string e1 = "");
void set_email();
void change_passwd();
void print_info();
static void print_n() { cout << "there are " << User::n << " users."; }
private:
string name, passwd, email;
static int n;
};
User::User(string n1, string p1, string e1) :name{ n1 }, passwd{ p1 }, email{ e1 }
{++n; }
int User::n = 0;
void User::set_email()
{
cout << "Enter email address: ";
string s;
cin >> s;
email = s;
cout << "email is set successfully..." << endl;
}
void User::change_passwd()
{
string c1;
cout << "Enter old password: ";
cin >> c1;
int count = 1;
while (c1 != passwd && count < 3)
{
cin >> c1;
count++;
if (count == 3)
cout << "password input error. Please try after a while." << endl;
}
if (count != 3)
{
cout << "Enter new passwd: ";
cin >> c1;
passwd = c1;
cout << "new passwd is set successfully..." << endl;
}
}
void User::print_info() {
cout << "name: " << name << endl;
cout << "passwd: ";
for (int i = 0; i < passwd.length(); i++)
cout << "*";
cout << endl;
cout << "email: " << email << endl;
}

#include "User.h"
#include <iostream>
// 测试User类
void test() {
using std::cout;
using std::endl;
cout << "testing 1......n";
User user1("Jonny", "92197", "xyz@hotmail.com");
user1.print_info();
cout << endl
<< "testing 2......nn";
User user2("Leonard");
user2.change_passwd();
user2.set_email();
user2.print_info();
cout << endl;
User::print_n();
}
int main() {
test();
}```