面向对象程序设计 实验一 类与对象

#ifndef _Complex

#include <iostream>
#include <cmath>

class Complex
{
public:

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

    Complex() = default;
    Complex(double i) :real(i),imag(0) {};
    Complex(double i, double j):real(i), imag(j) {};
    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 
    {
        if (imag > 0)
            std::cout << real << " + " << imag << 'i';
        else if (imag == 0)
            std::cout << real;
        else
            std::cout << real <<" - "<< abs(imag) <<'i';
    }
    void add(const Complex &other)
    {
        real += other.real;
        imag += other.imag;
    }
private:
    double real;
    double imag;
};

Complex add(const Complex c1, const Complex c2)
{
    Complex Complex_tem;
    Complex_tem.real = c1.real + c2.real;
    Complex_tem.imag = c1.imag + c2.imag;

    return Complex_tem;
}

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

double abs(const Complex c1)
{
    return sqrt(c1.real * c1.real + c1.imag * c1.imag);
}
#endif 

 

#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;
}

 

改换数据后

 

 Task 4

#ifndef _User.hpp
#include <iostream>
#include<string>

using std::string;

class User
{
public:
    User(string new_name) :
        name(new_name), passwd("111111"), email("") { n++; };
    User(string new_name, string new_passwd, string new_email) :
        name(new_name), passwd(new_passwd), email(new_email) {n++;};
    
    static void print_n() { std::cout <<"There are "<< User::n <<" users."<< std::endl; }
    void set_email();
    bool email_is_legal(string new_string);
    bool passwd_is_legal(string new_string);
    void change_passwd();
    void print_info();

private:
    string name;
    string passwd;
    string email;
    static int n;
};
int User::n = 0;

bool User::email_is_legal(string new_string)//检验是否字符串中有且只有一个@
{
    int i, j;
    i=new_string.find('@');
    j = new_string.rfind('@');
    if (i == j)
        return true;
    return false;
}

bool User::passwd_is_legal(string new_string)
{
    int len = new_string.size();
    if (len < 6||len>12)
    {
        return false;
    }
    return true;
}

void User::set_email()
{
    string new_email;
    std::cout << "Enter email address: ";
    std::cin >> new_email;
    if (email_is_legal(new_email))
    {
        email = new_email;
        std::cout << "email is set successfully... " << std::endl;
    }
    else
    {
        std::cout << "Your new email address is illegal, email cannot be set correctly..." << std::endl;
    }
}

void User::change_passwd()
{
    string tem_passwd;
    std::cout << "Enter old password: ";
    for (int i = 0; i < 3; i++)
    {
        std::cin >> tem_passwd;
        if (passwd != tem_passwd&&i!=2)
        {
            std::cout << "password input error. Please re_enter again: ";
            continue;
        }
        if (i == 2)
            break;
        std::cout << "enter new passwd: ";
        std::cin >> tem_passwd;
        
        if (passwd_is_legal(tem_passwd))
        {
            passwd = tem_passwd;
            std::cout << "passwd is set successfully... " << std::endl;
        }
        else
            std::cout << "your new passwd is illegal..." << std::endl;
        return;
    }
    std::cout << "password input error. Please try after a while. " << std::endl;
}

void User::print_info()
{
    std::cout <<"用户名: "<<name << std::endl;
    std::cout << "密码: ******"<< std::endl;
    std::cout << "联系邮箱: " << email << std::endl;
}
#endif 

 

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

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();
}

输入了不符合规定的新密码后：

输入了符合规定的新密码后：

 

 

 实验总结：

添加了额外两个功能，能够简单的判断新密码与邮箱是否合法，新密码规定长度须在6字节以上12字节以下，邮箱规定为必须出现一个@。

编程时在静态函数静态成员部分还是遇到了些问题，例如：

　　在task4中，函数print_n（），在声明的时候必须加上static，不然会报错，原因是静态成员只能由静态函数进行访问，这一点需要在以后注意。