实验一 类与对象

Complex.hpp:

#ifndef COMPLEX_HPP
#define EMPLOYEE_HPP
#include<iostream>
#include<math.h>
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 double abs(const Complex & p);
public:
    Complex (){}
    Complex(double a, double b = 0) :real(a), imag(b) {};
    Complex(const Complex& p);
    ~Complex() = default;
    double get_real()const
    {
        return real;
    }
    double get_imag()const
    {
        return imag;
    }
    void show()const
    {
        if (imag == 0)
        {
            cout << real << endl;
        }
        else if (imag < 0)
        {
            cout << real << "-" << abs(imag) << "i" << endl;
        }
        else
        cout << real << "+" << imag << "i" << endl;
    }
    void add(const Complex &p)
    {
        real += p.real;
        imag += p.imag;
    }
private:
    double real, imag;
};

Complex::Complex(const Complex& p)
{
    real = p.real;
    imag = p.imag;
}

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

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

double abs(const Complex & p)
{
    return sqrt(p.imag * p.imag + p.real * p.real);
}
#endif

Complex.cpp

#include "Complex.hpp"
#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;
    c4 = add(c1, c2);
    cout << "c4 = c1 + c2 = ";
    c4.show();
    cout << endl;

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

 

User.hpp:

#ifndef USER_HPP
#define USER_HPP
#include<iostream>
#include<string>
using namespace std;
class User
{
    static int number;
public:
    User(string name, string passwd = "111111", string email = "") :name(name), password(passwd), email(email) 
    { number++; }
    ~User() = default;
    void set_email()
    {
        cout << "Enter email address: ";
        cin >> email;
        cout << "email is set successfully..." << endl;
    }
    void change_passwd()
    {
        cout << "Enter old password: ";
        string old;
        int ret = 3;
        while (ret--)
        {
            cin >> old;
            if (old == password)
            {
                cout << "new passwd is set successfully..." << endl;
                break;
            }
            else if (!ret)
            {
                cout << "password input error. Please try after a while." << endl;
            }
            else
            cout << "password input error. Please re-enter again: ";
        }
    }
    void print_info()
    {
        cout << "name: " << name << endl;
        cout << "passwd:  ******" << endl;
        cout << "email: " << email << endl;
    }
     static void print_n()
    {
        cout << "there are " << number << " users." << endl;
    }
private:
    string name;
    string password;
    string email;
};
int User::number = 0;
#endif

task4.cpp:

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

int main()
{
using namespace std;

cout << "testing 1......" << endl;
User user1("Nigel", "88488848", "wkc@123.com");
user1.print_info();

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

User::print_n();
}

运行结果截图：

 实验总结：

按照指定函数编写类需要留意的地方有很多，成员函数和友元函数的定义要准确，每个变量的作用域和存放地点要弄清楚。