实验二

task 4

Complex.hpp

#pragma once
#include <iostream>
#include <cmath>
using namespace std;
class Complex {
    friend Complex add(const Complex &c1, const Complex &c2);
    friend bool is_equal(const Complex &c1, const Complex &c2);
    friend float abs(const Complex &c);
public:
    // 构造函数 
    Complex() : real(0), imag(0) {}
    Complex (float r) : real(r), imag(0) {}
    Complex (float r, double i) : real(r), imag(i) {}
    Complex (const Complex &c){
        this->real = c.real;
        this->imag = c.imag;
    } 
    float get_real() const{
        return real;
    }
    float get_imag() const{
        return imag;
    }
    void show() const{
        float i = fabs(imag);
        if(imag >= 0){
            cout << real << " + " << i << 'i' << endl;
        }else {
            cout << real << " - " << i << 'i' << endl;
        }
    }  //用于输出复数。要求以 3 + 4i ， 3 - 4i 这样的形式输出
    void add(const Complex &c){
        real += c.real;
        imag += c.imag;
    }
public:
    float real;
    float imag;
};

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

bool is_equal(const Complex &c1,const Complex&c2){
    return c1.real == c2.real && c1.imag == c2.imag;
}

float abs(const Complex &c){
    return sqrt(c.real * c.real + c.imag * c.imag);
}

.cpp

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

// 类测试
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;
    c4 = add(c1, c2);
    cout << "c4 = c1 + c2 = ";
    c4.show();
    cout << endl;

    c1.add(c2);
    cout << "c1 += c2, " << "c1 = ";
    c1.show();
    cout << endl;
}

int main() {
    test();
}

 

 task 5

.hpp

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

class User {
public:
    User (string name) : name(name), passwd("111111"),email(""){
        n++;
    } 
    User(string name,string pwd,string email) :name(name), passwd(pwd),email(email) {
        n++;
    }
    void set_email(){
        cout << "Enter email address:" << endl;
        string e;
        cin >> e;
        email = e;
        cout << "emai is set successfully...";
    }
    void change_passwd(){
        int count = 0;
        string pwd;
        cout << "Enter old password:";
        cin >> pwd;
        while(pwd!=passwd){
            if(count==2){
                cout << "password input error.Please try after a while." << endl;
                break;
            }
            cout << "password input error.Please re-enter again: ";
            cin >> pwd;
            count++;
        }
    }
    void print_info(){
        cout << "name: " << name << endl;
        cout << "passwd: ";
        for (int i = 0; i < passwd.length(); i++)
            cout << '*';
        cout << endl;
        cout << "email: " << email << endl;
    }
    void static print_n(){
            cout<<"there are "<<n<<" users"<<endl;
    }
public:
    string name, passwd, email;
    static int n;
};

int User::n = 0;

.cpp

#include "User.hpp"
#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......\n\n";
        
    User user2("Leonard");
    user2.change_passwd();
    user2.set_email();
    user2.print_info();

    cout << endl;
    User::print_n();
}

int main() {
    test();
}

 

 小结：task5 静态成员n  类内声明  类外实现 ： int User::n=0;