实验2 类与对象(2)

一、实验内容：

实验任务4：

1.Complex.hpp:

#include <iostream>
#include <cmath>
using namespace std;
class Complex
{
public:
    Complex(double x = 0, double y = 0) : real{x}, imag{y} {}
    ~Complex() {}
    Complex(const Complex &m) : real{m.real}, imag{m.imag} {}
    double get_real() { return real; }
    double get_imag() const { return imag; }
    void show() const
    {
        if (imag > 0)
            cout << real << "+" << imag << "i" << endl;
        if (imag == 0)
            cout << real << endl;
        if (imag < 0)
            cout << real << imag << "i" << endl;
    }
    Complex add(const Complex &n)
    {
        real = n.real + real;
        imag = n.imag + imag;
        return Complex(real, imag);
    }
    friend Complex add(const Complex &p, const Complex &q)
    {
        double real = p.real + q.real;
        double imag = p.imag + q.imag;
        Complex r;
        r.real = real;
        r.imag = imag;
        return r;
    }
    friend bool is_equal(Complex &p, const Complex &q)
    {
        if ((p.real != q.real) || (p.imag != q.imag))
            return false;
        else
            return true;
    }
    friend double abs(Complex &h)
    {
        return sqrt(h.real * h.real + h.imag * h.imag);
    }

private:
    double real, imag;
};

2.测试cpp:

#include <iostream>
#include "task4 Complex.hpp"
// 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();
}

运行结果：

3.测试cpp(更换数据后)：

#include <iostream>
#include "task4 Complex.hpp"
// 类测试
void test()
{
    using namespace std;

    Complex c1(7, -1);
    const Complex c2(-2.5);
    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();
}

运行结果：

实验任务5：

1.User.hpp:

// User.hpp
#include <iostream>
#include <string>
#include <iomanip>
using namespace std;
class User
{
public:
    User(string x, string y = "111111", string z = "") : name(x), passwd(y), email(z) { n++; }
    ~User() { n--; }
    void set_email()
    {
        string m;
        cout << "Enter email address:";
        cin >> m;
        cout << "email is set successfully..." << endl;
        email = m;
    }
    void change_passwd()
    {
        string a;
        int i;
        cout << "Enter old passwd:";
        cin >> a;
        for (i = 1; i < 3 && a.compare(passwd) != 0; i++)
        {
            cout << "passwd input error.Please re-enter again:";
            cin >> a;
        }
        if (a.compare(passwd) != 0)

            cout << "passwd input error.Please try after a while." << endl;
        else
        {
            cout << "Enter new passwd:";
            cin >> a;
            cout << "new passwd is set successfully..." << endl;
            passwd = a;
        }
    }
    void print_info()
    {
        int length;
        length = passwd.length();
        cout << std::left << setw(8) << "name:" << name << endl;
        cout << std::left << setw(8) << "passwd:";
        for (int i = 1; i <= length; i++)
            cout << "*";
        cout << endl;
        cout << std::left << setw(8) << "email:" << email << endl;
    }
    static void print_n()
    {
        cout << "there are " << n << " users." << endl;
    }

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

2.测试cpp:

#include "task5 User.hpp"
#include <iostream>
// 测试User类
void test()
{
    using std::cout;
    using std::endl;

    cout << "testing 1......\n";
    User user1("Jonny", "92197", "[email protected]");
    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();
}

运行结果：

二、实验总结：

1.实验任务4的Complex初次撰写时，未注意到c2是一个const修饰的类，导致在测试代码时只要c2运用到的类成员函数都发生了错误。在之后，我修改了类Complex中有关成员函数，加上了const修饰，问题迎刃而解。

2.实验任务5的User撰写时，判断密码输入对错的循环体我书写错误，一开始以（i < 3 && a.compare(passwd) != 0）判断条件并且以if(i == 3)判断跳出位置，最后测试证明 此代码下即使第三次密码输入正确也会显示“try after a while”，最后索性用if( a.compare(passwd) != 0)判断，成功解决问题。