实验任务三

欢迎访问我的个人博客：

xzajyjs.cn

题目要求

根据实验要求，有一个成员函数为add，同时又有一个友元函数add，这两个用法和意义是不同的，需要注意。

main.cpp

#include <iostream>#include "func.hpp"using namespace std;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;return 0;}

func.hpp

#ifndef CPP_FUNC_HPP#define CPP_FUNC_HPP#include "iostream"#include "cmath"class Complex{double real, imag;public:Complex(){};Complex(double _real, double _imag = 0):real(_real), imag(_imag){};Complex(const Complex &_temp){real = _temp.real;imag = _temp.imag;};double get_real() const{return real;}double get_imag() const{return imag;}void show() const{if (imag > 0)std::cout << get_real() << " + " << get_imag() << "i";else if (imag < 0)std::cout << get_real() << " - " << (-1) * get_imag() << "i";elsestd::cout << get_real();}void add(Complex x);// 注意constfriend Complex add(const Complex &x, const Complex &y);friend bool is_equal(const Complex &x, const Complex &y);friend double abs(Complex &x);};void Complex::add(Complex x) {imag += x.get_imag();real += x.get_real();}Complex add(const Complex &x, const Complex &y){Complex temp;temp.real = x.get_real() + y.get_real();temp.imag = x.get_imag() + y.get_imag();return temp;}bool is_equal(const Complex &x, const Complex &y){if(x.get_imag() == y.get_imag() && x.get_real() == y.get_real())return true;elsereturn false;}double abs(Complex &x){double value;value = sqrt(x.imag * x.imag + x.real * x.real);return value;}#endif //CPP_FUNC_HPP

实验任务四

题目

整体观察，要完成以上基本功能是没有一个部分有难度的。但对于密码、邮箱的审查是需要了解一定的正则表达式的基础的(下面代码中会有体现)。另外，由于是c++的缘故，对于密码的加密存储(不仅是后端数据库，更是源文件本身)是比较复杂的。如果后端是php则应在前端向后端传输的过程中就进行md5等非对称hash加密，以确保数据的安全。另外，对于密码也应有严格的审查(例如最小位数、特殊字符、大小写、数字等)，而在这里给出的源码只是对其进行了基础的位数验证，同样利用正则表达式是可以达到这样的效果的。对邮箱的验证是比较严格的，对于邮箱后缀进行了字典式匹配，仅支持几种常见的邮箱服务商。

main.cpp

#include "func.hpp"#include <iostream>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();}

func.hpp

#ifndef CPP_FUNC_HPP#define CPP_FUNC_HPP#include <iostream>#include <regex>class User{std::string name, passwd, email;static int n;public:User(std::string _name, std::string _passwd="111111", std::string _email=""):name(_name), passwd(_passwd), email(_email){n++;};void set_email();void change_passwd();void print_info() const{std::cout << "name:\\t" << name << std::endl;std::cout << "passwd:\\t" << "******" << std::endl;std::cout << "email:\\t" << email << std::endl;}static void print_n(){std::cout << "there are " << n << " users";}};// 记录对象数int User::n = 0;void User::set_email(){std::string _email;int times = 3;while(times--){std::cout << "Enter email address: ";std::cin >> _email;// 正则匹配，对邮箱合法性进行判断bool value = regex_match(_email, std::regex("\\\\w+?@(qq|gmail|163|126|yahoo|msn|hotmail|live)\\\\.(com|net|cn)"));if (value && _email != email){email = _email;std::cout << "email is set successfully..." << std::endl;break;}else{if(!times) std::cout << "Incorrect email format. Please try after a while." << std::endl;std::cout << "Incorrect email format.";}}}void User::change_passwd(){std::string _tempass;int times = 3, time = 3;std::cout << "Enter old password: ";while(times--){std::cin >> _tempass;// 验证通过。修改密码if(_tempass == passwd){while(time--){std::cout << "Enter new passwd:" ;std::cin >> _tempass;// 正则匹配，密码长度需大于等于6位bool value = regex_match(_tempass, std::regex(".{6}.*"));// 且不能和旧密码相同if (value && _tempass != passwd){passwd = _tempass;std::cout << "new passwd is set successfully..." << std::endl;break;}elsestd::cout << "your passwd is too simple!" << std::endl;}break;}// 旧密码错误else{if (times == 0) {std::cout << "password input error. Please try after a while." << std::endl;break;}else std::cout << "password input error. Please re-enter again: ";}}}#endif //CPP_FUNC_HPP

总结

• 对于代码的安全性应时刻注意，权限的细分、最小化原则。
• 数据存储的安全性很重要。从源码开始就应该进行非对称加密。
• 正则表达式在实际场景中有着广泛的应用。
• 接口的完备性是常常缺乏考虑的一点，一个成熟的接口应具备应对各种输入并进行合理的反馈。如存在漏洞则会变得非常危险。
• 友元函数的定义和适用范围、条件等需要明确，