实验一 类与对象

#ifndef Complex_hpp
#define Complex_hpp
#include<iostream>
#include<cmath>
using namespace std;
class Complex{
    public:
    Complex();    
    Complex(double a)
    {
        real=a;
        imag=0;
    }
    Complex(double a,double b){
        real=a;
        imag=b;
    }
    Complex(Complex &c);
    ~Complex(){}
    double get_real() const;
    double get_imag() const;  
    void show();
    void show() const;
    void add(const Complex &c );
    friend Complex add(Complex &c1,const Complex &c2);
    friend bool is_equal(Complex &c1,const Complex &c2);
    friend double abs(Complex &c1);
    private:
    double real,imag;    
};
Complex::Complex():real(0),imag(0){
}
Complex::Complex(Complex &c)
{
    real=c.get_real();
    imag=c.get_imag();
}
double Complex::get_real() const{
    return real;
}
double Complex::get_imag() const{
    return imag;
}
void Complex::show(){
    if(imag>0)
    cout<<real<<"+"<<imag<<"i";
    else if(imag==0)
    cout<<real;
    else
    cout<<real<<imag<<"i";
}
void Complex::show() const{
    if(imag>0)
    cout<<real<<"+"<<imag<<"i";
    else if(imag==0)
    cout<<real;
    else
    cout<<real<<imag<<"i";
}
void Complex::add(const Complex &c){
    real+=c.get_real();
    imag+=c.get_imag();
}
Complex add(Complex &c1,const Complex &c2)
{
    Complex t(0,0);
    t.real=c1.real+c2.real;
    t.imag=c1.imag+c2.imag;
    return t;
}
bool is_equal(Complex &c1,const Complex &c2)
{
    if(c1.real==c2.real&&c1.imag==c2.imag)
    return true;
    else
    return false;
}
double abs(Complex &c)
{
    return sqrt(c.real*c.real+c.imag*c.imag); 
}
#endif

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

int main()
{
    using namespace std;

    Complex c1(2, -4);
    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;
}

#ifndef User_hpp
#define User_hpp
#include<iostream>
#include<string>
using namespace std;
class User{
public:
User();
User(string name0,string password0,string email0);
void set_email();
void change_passwd();
void print_info();
static void print_n();
private:
string name;
string password;
string email;
static int n;
};
int User::n=0;
User::User(){
n++;
}
User::User(string name0,string password0="111111",string email0="\0"):name{name0},password{password0},email{email0}
{
n++;
}
void User::set_email(){
cout<<"Enter email address: ";
string email0;
int len,i,flag=0;
cin>>email0;
len=email0.length();
for(i=0;i<len;i++)//判断邮箱合法性
{
if(email0[i]=='@')
flag=1;
if(email0[len-1]!='m'||email0[len-2]!='o'||email0[len-3]!='c'||email0[len-4]!='.')//结尾是.com
flag=0;
}
if(flag==1)
{
email=email0;
cout<<"email is set successfully..."<<endl;
}
else
{
cout<<"illegal email address"<<endl;
email="none email available ";}
}
void User::change_passwd(){
cout<<"Enter old password: ";
string password0,password1;
int count=0;
int flag=0,i;
while(count<3)
{
cin>>password0;
if(password0!=password)
{
count++;
if(count==3)
cout<<"password input error,please try after a while."<<endl;
else
cout<<"password input error,please re-enter again: " ;
}
else
{
cout<<"Enter new passed: ";
cin>>password1;
password=password1;
cout<<"new passwd is set sucessfully..."<<endl;
break;
}
}
}
void User::print_info()
{
cout<<"name: "<<name<<endl;
cout<<"passwd: ******"<<endl;
cout<<"email: "<<email<<endl;
}
void User::print_n()
{
cout<<"there are "<<n<<" user";
if(n>1)
cout<<"s"<<endl;
}
#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();
}

 

 实验总结：

  实验三要构造的函数不难，但因为没注意到c2是const修饰的让我卡了很长时间。如果函数中含有用const修饰的参数，一定要在形参中加入const修饰。

  实验四构造的类还没有实验三的复杂，主要要关注string类在类中的应用。如果对string类有些了解，写起来困难不大。