实验一 类与对象

 

 

 Complex.hpp

#ifndef COMPLEX_HPP
#define COMPLEX_HPP

#include<iostream>
#include<cmath>
using namespace std;
class Complex{
    private:
        double real,imag;
    public:
    Complex (double real0=0,double imag0=0):real(real0),imag(imag0){}
    double get_real()const{return real;}
    double get_imag()const{return imag;}    
    void show()const;
    Complex(const Complex &p);
    friend Complex add(Complex a,Complex b);
     void add(const Complex &p);
    friend bool is_equal(const Complex &a,const Complex &b);
    friend double abs(const Complex &p);
    
};
void Complex::show()const{
    if(imag!=0) 
    cout<<real<<imag<<"i";
    else
    cout<<real;
}
Complex::Complex(const Complex &p){
    real=p.real;
    imag=p.imag;
}
void Complex::add(const Complex &p){
real=real+p.real;
imag=imag+p.imag;
}
Complex add(Complex a,Complex b){
    a.real=a.real+b.real;
    a.imag=a.imag+b.imag;
    return a;
}
bool is_equal(const Complex &a,const Complex &b){
    if(a.real==b.real&&a.imag==b.imag)
    return true;
    else
    return false;
}
double abs(const Complex &p){
    return sqrt    (pow(p.real,2)+pow(p.imag,2));
}

#endif

 

 task3.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;
}

 

task3运行截图

 

  User.hpp

#ifndef USER_HPP
#define USER_HPP

#include <iostream>
#include <string> 

using namespace std; 
class User{
    private:
        string name;
        string passwd;
        string email;
        static int n;
    public:
        User(string name0);
        User(string name0,string passwd0,string email0);
        void set_email();
        void change_passwd();
        void print_info();
        static void print_n();
};
int User::n=0;
User::User(string name0):name(name0),passwd("111111"),email("\0"){
    ++n;
}
User::User(string name0,string passwd0,string email0):name(name0),passwd(passwd0),email(email0){
    ++n;
}
void User::print_info(){
    cout<<name<<endl;
    cout<<"******"<<endl;
    cout<<email<<endl;
}
void User::change_passwd(){
    cout<<"Enter old password:";
    string pa;
    cin>>pa;
    for(int i=1;i<=3;i++)
    {
        if(i!=3&&pa!=passwd)
        {
            cout<<"password input error.Please re-enter again:";
            cin>>pa;
        }
        if(i==3&&pa!=passwd)
        {
            cout<<"password input error.Please try after a while."<<endl;
        }
    }
}
void User::set_email(){
    cout<<"Enter email adress:";
    string a;
    cin>>a;
    email=a;
    cout<<"email is set successfully..."<<endl;
}
void User::print_n(){
    cout<<"there are "<<n<<" users.";
}
#endif

#include "User.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();
}

 

task4运行截图

 

 实验总结：

1、可以用setfill()和setw()来排版，其中setfill()为永久有效，直至下一个setfill（），而setw（）为一次有效；

2、static修饰的可以直接用类名访问；

3、const的使用可以保护数据还能防止友元函数的无法识别。