实验2 现代c++编程初体验

task1：

#pragma once

#include<string>

//类T声明
class T{
public:
    T(int x=0,int y=0);//普通构造函数
    T(const T&t);//复制构造函数
    T(T &&t);//移动构造函数
    ~T();
    
    void adjust(int ratio);//按系数成倍调整数据
    void display() const;//以（m1,m2）形式显示T类对象信息
    
private:
    int m1,m2; 
 

//类属性、方法
public:
    static int get_cnt();//显示当前T类对象总数

public:
    static const std::string doc;//类T的描述信息 
    static const int max_cnt; //类T对象上限 
    
private:
    static int cnt;//当前T类对象数目
    
//类T友元函数声明
    friend void func(); 
};

//普通函数声明
void func();

#include"T.h"
#include<iostream>
#include<string>
//类T实现

//static成员数据类外初始化 
const std::string T::doc{"a simple class sample"};
const int T::max_cnt=999;
int T::cnt=0;

//类方法 
int T::get_cnt(){
    return cnt;
} 

//对象方法
T::T(int x,int y):m1{x},m2{y}{
    ++cnt;
    std::cout<<"T constructor called.\n";
} 

T::T(const T &t): m1{t.m1}, m2{t.m2} {
    ++cnt;
    std::cout << "T copy constructor called.\n";
}

T::T(T&&t):m1{t.m1},m2{t.m2}{
    ++cnt;
    std::cout<<"T move constructor called.\n";
}

T::~T(){
    --cnt;
    std::cout<<"T destructor called.\n";
}

void T::adjust(int ratio){
    m1*=ratio;
    m2*=ratio;
}
void T::display()const{
    std::cout<<"("<<m1<<","<<m2<<")";
}

//普通函数实现
void func(){
    T t5(42);
    t5.m2=2049;
    std::cout<<"t5=";
    t5.display();
    std::cout<<'\n';
}

#include "T.h"
#include <iostream>

void test_T();

int main() {
    std::cout << "test Class T: \n";
    test_T();
    
    std::cout << "\ntest friend func: \n";
    func();
}

void test_T() {
    using std::cout;
    using std::endl;
    
    cout << "T info: " << T::doc << endl;
    cout << "T objects'max count: " << T::max_cnt << endl;
    cout << "T objects'current count: " << T::get_cnt() << endl << endl;
    
    T t1;
    cout << "t1 = "; t1.display(); cout << endl;
    
    T t2(3, 4);
    cout << "t2 = "; t2.display(); cout << endl;
    
    T t3(t2);
    t3.adjust(2);
    cout << "t3 = "; t3.display(); cout << endl;
    
    T t4(std::move(t2));
    cout << "t4 = "; t4.display(); cout << endl;
    
    cout << "test: T objects'current count: " << T::get_cnt() << endl;
}

问题1：YES

问题2：普通构造函数功能：对类对象进行初始化  调用时机：定义一个类对象的时候 

             复制构造函数功能：用一个已经定义了的类对象去初始化另一个类对象  调用时机：用类对象初始化新的类对象

              移动构造函数功能：将一个初始化过的对象转移给另一个对象  调用时机：用右值初始化新的对象

              析构函数功能：释放对象占有的资源  调用时机：该对象生命周期结束的时候

问题3：可以正常运行

 

tsak2:

 

#pragma once

#include<string>

class complex{
public:
    static const std::string doc;
    
private:
    double real;
    double imag;
    
public:
    complex(double x=0.0,double y=0.0);
    complex(const complex&c);
    
    double get_real()const;
    double get_imag()const;
    void add(const complex& c);
    
     friend void output(const complex& c);
     friend double abs(const complex& c);
     friend complex add(const complex& c1,const complex& c2);
     friend bool is_equal(complex x,complex y);
     friend bool is_not_equal(complex a,complex b); 
};

#include"complex.h"
#include<iostream>
#include<string>
#include<cmath>

const std::string complex::doc{"a simplified complex class"};

complex::complex(double x,double y):real{x},imag{y}{};
complex::complex(const complex&c):real{c.real},imag{c.imag}{};

double complex::get_real()const{
    return real;
}
double complex::get_imag()const{
    return imag; 
}
void complex::add(const complex& c){
    real+=c.real;
    imag+=c.imag;
}

void output(const complex& c){
    if(c.imag>=0)
    std::cout<<c.real<<"+"<<c.imag<<"i";
    else
    std::cout<<c.real<<c.imag<<"i";
}
double abs(const complex& c){
    return std::sqrt(c.real*c.real+c.imag*c.imag);
}
complex add(const complex& c1,const complex& c2){
    return complex(c1.real+c2.real,c1.imag+c2.imag);
}
bool is_equal(complex c1,complex c2){
    if((c1.real==c2.real)&&(c1.imag==c2.imag))
    return true;
    else
    return false;
}
bool is_not_equal(complex c1,complex c2){
    if((c1.real==c2.real)&&(c1.imag==c2.imag))
    return false;
    else
    return true;
}

#include"complex.h"
#include <iostream>
#include <iomanip>
#include <complex>

void test_complex();
void test_std_complex();


int main() {
    std::cout << "*******测试1: 自定义类Complex*******\n";
    test_complex();
    
    std::cout << "\n*******测试2: 标准库模板类complex*******\n";
    test_std_complex();
}

void test_complex() {
    using std::cout;
    using std::endl;
    using std::boolalpha;
    
    
    cout << "类成员测试: " << endl;
    cout << complex::doc << endl << endl;
    
    
    cout << "Complex对象测试: " << endl;
    complex c1;
    complex c2(3, -4);
    complex c3(c2);
    complex c4 = c2;
    const complex c5(3.5);

    cout << "c1 = "; output(c1); cout << endl;
    cout << "c2 = "; output(c2); cout << endl;
    cout << "c3 = "; output(c3); cout << endl;
    cout << "c4 = "; output(c4); cout << endl;
    cout << "c5.real = " << c5.get_real()
    << ", c5.imag = " << c5.get_imag() << endl << endl;
    
    cout << "复数运算测试: " << endl;
    cout << "abs(c2) = " << abs(c2) << endl;
    c1.add(c2);
    cout << "c1 += c2, c1 = "; output(c1); cout << endl;
    cout << boolalpha;
    cout << "c1 == c2 : " << is_equal(c1, c2) << endl;
    cout << "c1 != c2 : " << is_not_equal(c1, c2) << endl;
    c4 = add(c2, c3);
    cout << "c4 = c2 + c3, c4 = "; output(c4); cout << endl;
}


void test_std_complex() {
    using std::cout;
    using std::endl;
    using std::boolalpha;
    
    cout << "std::complex<double>对象测试: " << endl;
    std::complex<double> c1;
    std::complex<double> c2(3, -4);
    std::complex<double> c3(c2);
    std::complex<double> c4 = c2;
    const std::complex<double> c5(3.5);
    
    
    cout << "c1 = " << c1 << endl;
    cout << "c2 = " << c2 << endl;
    cout << "c3 = " << c3 << endl;
    cout << "c4 = " << c4 << endl;
    
    
    cout << "c5.real = " << c5.real()
    << ", c5.imag = " << c5.imag() << endl << endl;
    
    
    cout << "复数运算测试: " << endl;
    cout << "abs(c2) = " << abs(c2) << endl;
    c1 += c2;
    cout << "c1 += c2, c1 = " << c1 << endl;
    cout << boolalpha;
    cout << "c1 == c2 : " << (c1 == c2)<< endl;
    cout << "c1 != c2 : " << (c1 != c2) << endl;
    c4 = c2 + c3;
    cout << "c4 = c2 + c3, c4 = " << c4 << endl;
}

问题1：标准库模板类的形式更简洁。 有关联 例如add(c1+c2)从运算的层面来说就是计算c1+c2

问题2-1：可以不访问，因为提供了共有的get_real()和get_imag()函数，可以由此获得数据

问题2-2：没有

问题2-3：必须要访问私有数据并且没有公有函数接口可以获得数据的时候

问题3：显式声明构造函数

 

task3:

#pragma once
#include <string>

enum class ControlType {Play, Pause, Next, Prev, Stop, Unknown};

class playercontrol {
public:
    playercontrol();
    
    ControlType parse(const std::string& control_str); // 实现std::string -->ControlType转换
    
    void execute(ControlType cmd) const; // 执行控制操作（以打印输出模拟）
    
    static int get_cnt();
    
private:
    static int total_cnt;
};

#include "playercontrol.h"
#include <iostream>
#include <algorithm>
#include<string>
#include<cctype>

int playercontrol::total_cnt = 0;
playercontrol::playercontrol() {}

ControlType playercontrol::parse(const std::string& control_str) {
    total_cnt+=1;
    int len=control_str.length();
    std::string control_strtemp;
    control_strtemp=std::toupper(control_str[0]);
    for(int i=1;i<len;++i)
    control_strtemp+=std::tolower(control_str[i]);
    
    if(control_strtemp=="Play")
    return ControlType::Play;
    else if(control_strtemp=="Pause")
    return ControlType::Pause;
    else if(control_strtemp=="Next")
    return ControlType::Next;
    else if(control_strtemp=="Prev")
    return ControlType::Prev;
    else if(control_strtemp=="Stop")
    return ControlType::Stop;
    else
    return ControlType::Unknown;
    
}
void playercontrol::execute(ControlType cmd) const {
    switch (cmd) {
    case ControlType::Play: std::cout << "[play] Playing music...\n"; break;
    case ControlType::Pause: std::cout << "[Pause] Music paused\n"; break;
    case ControlType::Next: std::cout << "[Next] Skipping to next track\n"; break;
    case ControlType::Prev: std::cout << "[Prev] Back to previous track\n"; break;
    case ControlType::Stop: std::cout << "[Stop] Music stopped\n"; break;
    default: std::cout << "[Error] unknown control\n"; break;
    }
}
    
int playercontrol::get_cnt() {
    return total_cnt;
} 

#include "playercontrol.h"
#include <iostream>
void test() {
    playercontrol controller;
    std::string control_str;
    std::cout << "Enter Control: (play/pause/next/prev/stop/quit):\n";
    
    while(std::cin >> control_str) {
    if(control_str == "quit")
    break;
    
    ControlType cmd = controller.parse(control_str);
    controller.execute(cmd);
    std::cout << "Current Player control: " << playercontrol::get_cnt() << "\n\n";
    }
}

int main() {
    test();
}

 

task4：

#pragma once

#include<string>

class Fraction{
public:
    static const std::string doc;
    
private:
    int up;
    int down;
    
public:
    Fraction();
    Fraction(int x,int y=1);
    Fraction(const Fraction& f);
    
    int get_up();
    int get_down();
    Fraction negative();
    int gcd();//求分母和分子的最大公约数 
    int judge();//判断分数的正负 
    
    
    friend void output(Fraction f);
    friend Fraction add(Fraction f1,Fraction f2);
    friend Fraction sub(Fraction f1,Fraction f2);
    friend Fraction mul(Fraction f1,Fraction f2);
    friend Fraction div(Fraction f1,Fraction f2);
    
};

#include"Fraction.h"
#include<iostream>
#include<algorithm>

const std::string Fraction::doc{"Fraction类v0。01版\n目前仅支持分数对象的构造、输出、加/减/乘/除运算"};

Fraction::Fraction(){}
Fraction::Fraction(int x,int y):up{x},down{y}{}
Fraction::Fraction(const Fraction& f):up{f.up},down{f.down}{} 

//求分母和分子的最大公约数 
int Fraction::gcd(){
    int temp;
    int a=std::abs(up);
    int b=std::abs(down);
    while(b!=0){
        temp=b;
        b=a%b;
        a=temp;
    }
    return a;
}

//判断分数正负
int Fraction::judge(){
    if(up*down>0)
    return 1;
    else if(up*down<0) 
    return -1;
    else 
    return 0;
} 

//返回分子 
int Fraction::get_up(){
    return up; 
}

//返回分母 
int Fraction::get_down(){
    return down;
}

//求负 
Fraction Fraction::negative(){
    if(judge()>0&&gcd()!=1){
        up/=gcd();
        down/=gcd();
    }
    else if(judge()<0&&gcd()!=1){
        up/=gcd();
        down/=gcd();
    }
    if(judge()==1)
    return Fraction(std::abs(up)*(-1),std::abs(down));
    else if(judge()==-1)
    return Fraction(std::abs(up),std::abs(down));
    else 
    return Fraction(0);
}


//输出分数 
void output(Fraction f){
    if(f.judge()>0&&f.gcd()!=1){
        f.up/=f.gcd();
        f.down/=f.gcd();
    }
    else if(f.judge()<0&&f.gcd()!=1){
        f.up/=f.gcd();
        f.down/=f.gcd();
    }
    
    if(f.judge()==1){
        if(f.down==1)
        std::cout<<std::abs(f.up)<<std::endl;
        else
        std::cout<<std::abs(f.up)<<"/"<<std::abs(f.down)<<std::endl;
    }
    else if(f.judge()==-1){
        if(f.down==1)
        std::cout<<"-"<<std::abs(f.down)<<std::endl;
        else
        std::cout<<"-"<<std::abs(f.up)<<"/"<<std::abs(f.down)<<std::endl;
    }
    else if(f.judge()==0&&f.down!=0){
        std::cout<<"0"<<std::endl;
    }
    else 
    std::cout<<"分母不能为0"; 
}

//加法 
Fraction add(Fraction f1,Fraction f2){
    Fraction t;
    int a=std::abs(f1.up);
    int b=std::abs(f1.down);
    int c=std::abs(f2.up);
    int d=std::abs(f2.down);
    
    if(f1.judge()==0&&f2.judge()==0)
    return Fraction(0);
    else if(f1.judge()==0)
    return f2;
    else if(f2.judge()==0)
    return f1;
    
    t.down=b*d;
    if(f1.judge()==1&&f2.judge()==1){
        t.up=a*d+b*c;
        if(t.gcd()!=1){
            t.up/=t.gcd();
            t.down/=t.gcd();
        }
        return t;
    }
    else if(f1.judge()==1&&f2.judge()==-1){
        t.up=a*d-b*c;
        if(t.gcd()!=1){
            t.up/=t.gcd();
            t.down/=t.gcd();
        }
        if(t.judge()>0) 
        return t;
        else if(t.judge()<0)
        return Fraction(std::abs(t.up)*(-1),std::abs(t.down));
        else 
        return Fraction(0);
    }
    else if(f1.judge()==-1&&f2.judge()==1){
        t.up=c*b-a*d;
        if(t.gcd()!=1){
            t.up/=t.gcd();
            t.down/=t.gcd();
        }
        if(t.judge()>0) 
        return t;
        else if(t.judge()<0)
        return Fraction(std::abs(t.up)*(-1),std::abs(t.down));
        else 
        return Fraction(0);
    }
    else{
        t.up=(a*d+b*c)*(-1);
        if(t.gcd()!=1){
            t.up/=t.gcd();
            t.down/=t.gcd();
        }
        return Fraction(std::abs(t.up)*(-1),std::abs(t.down));
    }
    
}

//减法 
Fraction sub(Fraction f1,Fraction f2){
    Fraction t;
    if(f1.judge()==0&&f2.judge()==0)
    return Fraction(0);
    else if(f1.judge()==0)
    return f2.negative();
    else if(f2.judge()==0)
    return f1;
    
    t=f2.negative();
    return add(f1,t);
}

//乘法 
Fraction mul(Fraction f1,Fraction f2){
    Fraction t;
    if(f1.judge()==0||f2.judge()==0)
    return Fraction(0);
    
    t.down=std::abs(f1.down)*std::abs(f2.down);
    t.up=std::abs(f1.up)*std::abs(f2.up);
    if(t.gcd()!=1){
        t.up/=t.gcd();
        t.down/=t.gcd();
    }
    if(f1.judge()*f2.judge()>0)
    return t;
    else
    return Fraction(t.up*(-1),t.down);
}

//除法 
Fraction div(Fraction f1,Fraction f2){
    Fraction t;
    if(f2.judge()==0)
    return Fraction(0,0);
    
    if(f1.judge()==0)
    return Fraction(0);
    
    t.down=std::abs(f1.down)*std::abs(f2.up);
    t.up=std::abs(f1.up)*std::abs(f2.down);
    if(t.gcd()!=1){
        t.up/=t.gcd();
        t.down/=t.gcd();
    }
    if(f1.judge()*f2.judge()>0)
    return t;
    else
    return Fraction(t.up*(-1),t.down);
}

#include"Fraction.h"
#include <iostream>

void test1();
void test2();

int main() {
    std::cout << "测试1: Fraction类基础功能测试\n";
    test1();
    
    std::cout << "\n测试2: 分母为0测试: \n";
    test2();
}

void test1() {
    using std::cout;
    using std::endl;
    
    cout << "Fraction类测试: " << endl;
    cout << Fraction::doc << endl << endl;
    
    Fraction f1(5);
    Fraction f2(3, -4), f3(-18, 12);
    Fraction f4(f3);
    cout << "f1 = "; output(f1); cout << endl;
    cout << "f2 = "; output(f2); cout << endl;
    cout << "f3 = "; output(f3); cout << endl;
    cout << "f4 = "; output(f4); cout << endl;
    
    
    Fraction f5(f4.negative());
    cout << "f5 = "; output(f5); cout << endl;
    cout << "f5.get_up() = " << f5.get_up()
    << ", f5.get_down() = " << f5.get_down() << endl;
    
    
    cout << "f1 + f2 = "; output(add(f1, f2)); cout << endl;
    cout << "f1 - f2 = "; output(sub(f1, f2)); cout << endl;
    cout << "f1 * f2 = "; output(mul(f1, f2)); cout << endl;
    cout << "f1 / f2 = "; output(div(f1, f2)); cout << endl;
    cout << "f4 + f5 = "; output(add(f4, f5)); cout << endl;
}


void test2() {
    using std::cout;
    using std::endl;
    
    Fraction f6(42, 55), f7(0, 3);
    
    cout << "f6 = "; output(f6); cout << endl;
    cout << "f7 = "; output(f7); cout << endl;
    cout << "f6 / f7 = "; output(div(f6, f7)); cout << endl;
}

问题：我选择的是友元 友元可以直接访问类的私有成员 但是这个分数计算需要改变得到的分数的分子和分母的值，对于安全性有一定的影响