OOP-实验2
四、实验结论
1.task1
T.h
查看代码
#pragma once
#include <string>
// 类T: 声明
class T {
// 对象属性、方法
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(); // 析构函数
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();T.cpp
查看代码
#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';
}task1.cpp
#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;
}运行结果截图
问题1：No func() 是类外定义的友元函数，需要先声明
问题2：
T(int x = 0, int y = 0); 普通构造函数 在创建类T的对象时提供默认值，使没有提供参数的对象值为(0,0),例如task1.cpp中的line22和line25
T(const T &t); 复制构造函数 通过已有的T类对象来创建新的对象，实现对象的复制，将t的值传输给新对象，例如task1.cpp中的line28
T(T &&t); 移动构造函数 将已有对象的值移动给新对象，原对象将无效
~T(); 析构函数 释放对象的内存，当对象的生命周期结束或超出作用域调用时将自动调用
问题3：No 静态成员变量需要在类外单独定义初始化，否则链接失败
2.task2
Complex.h
查看代码
#ifndef COMPLEX_H
#define COMPLEX_H
#include<string>
class Complex {
private:
double real;
double imag;
public:
static const std::string doc;
Complex();
Complex(double r,);
Complex(double r,double i);
Complex(const Complex&other);
double get_real() const;
double get_imag() const;
void add(const Complex&other);
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(const Complex& c1,const Complex& c2);
friend bool is_not_equal(const Complex& c1,const Complex& c2);
};
void output(const Complex& c);
double abs(const Complex& c);
Complex add(const Complex& c1,const Complex& c2);
bool is_equal(const Complex& c1,const Complex& c2);
bool is_not_equal(const Complex& c1,const Complex& c2);
#endif Complex.cpp
查看代码
#include<iostream>
#include"Complex.h"
#include<cmath>
using namespace std;
const string Complex::doc="a simplified complex class";
Complex::Complex():real(0.0),imag(0.0){}
Complex::Complex(double r):real(r),imag(0.0){}
Complex::Complex(double r,double i):real(r),imag(i){}
Complex::Complex(const Complex&other):real{other.real},imag{other.imag}{}
double Complex:: get_real() const
{
return real;
}
double Complex:: get_imag() const
{
return imag;
}
void Complex::add(const Complex&other)
{
real+=other.real;
imag+=other.imag;
}
void output(const Complex&c)
{
cout<<c.real;
if(c.imag>=0)
{
cout<<"+"<<c.imag<<"i";
}
else
{
cout<<"-"<<-c.imag<<"i";
}
}
Complex add(const Complex&c1,const Complex&c2)
{
return Complex(c1.real+c2.real,c1.imag+c2.imag);
}
double abs(const Complex&c)
{
return sqrt(c.real*c.real+c.imag*c.imag);
}
bool is_equal(const Complex&c1,const Complex&c2)
{
return(c1.real==c2.real)&&(c1.imag==c2.imag);
}
bool is_not_equal(const Complex&c1,const Complex&c2)
{
return !is_equal(c1,c2);
}task2.cpp
查看代码
#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;
}运行结果截图
问题1：
标准库模板类complex更简洁。函数和内容的关联很强，因为标准库用了运算符重载。
问题2：
2-1：是的。output()需要访问实部和虚部来输出打印，abs()需要访问实部和虚部来取模，add()需要访问实部和虚部来相加。
2-2：查阅后得知，没有设置成友元。abs是独立的非成员函数。
2-3：当非成员函数需要访问private成员时
问题3：可以将拷贝构造函数设置为private，这样的话在类的外部无法访问它，编译器会报错。
3.task3
PlayerControl.h
查看代码
#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;
};PlayerControl.cpp
查看代码
#include "PlayerControl.h"
#include <iostream>
#include <algorithm>
int PlayerControl::total_cnt = 0;
PlayerControl::PlayerControl() {}
// 待补足
// 1. 将输入字符串转为小写，实现大小写不敏感
std::string toLower(const std::string&str)
{
std::string s=str;
std::transform(s.begin(),s.end(),s.begin(),[](unsigned char c)
{
return std::tolower(c);
}
);
return s;
}
// 2. 匹配"play"/"pause"/"next"/"prev"/"stop"并返回对应枚举
// 3. 未匹配的字符串返回ControlType::Unknown
// 4. 每次成功调用parse时递增total_cnt
ControlType PlayerControl::parse(const std::string& control_str)
{
std::string lstr=toLower(control_str);
if(lstr=="play")
{
total_cnt++;
return ControlType::Play;
}
else if(lstr=="pause")
{
total_cnt++;
return ControlType::Pause;
}
else if(lstr=="next")
{
total_cnt++;
return ControlType::Next;
}
else if(lstr=="prev")
{
total_cnt++;
return ControlType::Prev;
}
else if(lstr=="stop")
{
total_cnt++;
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;
}task3.cpp
查看代码
#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();
}运行结果截图
emoji输出
PlayerControl.h
查看代码
#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;
};PlayerControl.cpp
查看代码
#include "PlayerControl.h"
#include <iostream>
#include <algorithm>
int PlayerControl::total_cnt = 0;
PlayerControl::PlayerControl() {}
// 待补足
// 1. 将输入字符串转为小写，实现大小写不敏感
std::string toLower(const std::string&str)
{
std::string s=str;
std::transform(s.begin(),s.end(),s.begin(),[](unsigned char c)
{
return std::tolower(c);
}
);
return s;
}
// 2. 匹配"play"/"pause"/"next"/"prev"/"stop"并返回对应枚举
// 3. 未匹配的字符串返回ControlType::Unknown
// 4. 每次成功调用parse时递增total_cnt
ControlType PlayerControl::parse(const std::string& control_str)
{
std::string lstr=toLower(control_str);
if(lstr=="play")
{
total_cnt++;
return ControlType::Play;
}
else if(lstr=="pause")
{
total_cnt++;
return ControlType::Pause;
}
else if(lstr=="next")
{
total_cnt++;
return ControlType::Next;
}
else if(lstr=="prev")
{
total_cnt++;
return ControlType::Prev;
}
else if(lstr=="stop")
{
total_cnt++;
return ControlType::Stop;
}
else
{
return ControlType::Unknown;
}
}
void PlayerControl::execute(ControlType cmd) const {
switch (cmd) {
case ControlType::Play: std::cout << "\1F3B5 Playing music...\n"; break;
case ControlType::Pause: std::cout << "\23F8 Music paused\n"; break;
case ControlType::Next: std::cout << "\23ED Skipping to next track\n"; break;
case ControlType::Prev: std::cout << "\23EE Back to previous track\n"; break;
case ControlType::Stop: std::cout << "\23F9 Music stopped\n"; break;
default: std::cout << "\274C unknown control\n"; break;
}
}
int PlayerControl::get_cnt() {
return total_cnt;
}task3.cpp
查看代码
#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();
}
我按照emoji网站复制了编码，并且设置了编译器设置-finput-charset=UTF-8，还是无法成功输出结果......不知道是哪里出了问题，询问ai也是无果......
4.task4
Fraction.h
查看代码
#ifndef FRACTIONG_H
#define FRACTION_H
#include<string>
class Fraction
{
private:
int up;
int down;
void reduce();
int maxyueshu(int a, int b)const;
public:
static const std::string doc;
Fraction(int upp=0,int downn=1);
Fraction(const Fraction&other);
int get_up() const;
int get_down() const;
Fraction negative() const;
friend void output(const Fraction &f);
friend Fraction add(const Fraction &f1,const Fraction &f2);
friend Fraction sub(const Fraction &f1,const Fraction &f2);
friend Fraction mul(const Fraction &f1,const Fraction &f2);
friend Fraction div(const Fraction &f1,const Fraction &f2);
};
void output(const Fraction &f);
Fraction add(const Fraction &f1,const Fraction &f2);
Fraction sub(const Fraction &f1,const Fraction &f2);
Fraction mul(const Fraction &f1,const Fraction &f2);
Fraction div(const Fraction &f1,const Fraction &f2);
#endifFraction.cpp
查看代码
#include "Fraction.h"
#include<iostream>
#include<cmath>
#include<stdexcept>
using namespace std;
const string Fraction::doc="Fraction类 v 0.01版. \n目前仅支持分数对象的构造、输出、加/减/乘/除运算.";
int Fraction::maxyueshu(int a,int b) const
{
a=abs(a);
b=abs(b);
while(b!=0)
{
int t=b;
b=a%b;
a=t;
}
return a;
}
void Fraction::reduce()
{
if(down==0)
return;
int yue=maxyueshu(up,down);
up/=yue;
down/=yue;
if(down<0)
{
up=-up;
down=-down;
}
}
Fraction::Fraction(int upp,int downn):up(upp),down(downn)
{
reduce();
}
Fraction::Fraction(const Fraction& other) : up(other.up), down(other.down){}
int Fraction::get_up() const
{
return up;
}
int Fraction::get_down() const
{
return down;
}
Fraction Fraction::negative() const
{
return Fraction(-up, down);
}
void output(const Fraction& f)
{
if (f.down == 0)
{
return;
}
if (f.down == 1)
{
cout << f.up;
}
else
{
cout << f.up << "/" << f.down;
}
}
Fraction add(const Fraction& f1, const Fraction& f2)
{
int new_up = f1.up * f2.down + f2.up * f1.down;
int new_down = f1.down * f2.down;
return Fraction(new_up, new_down);
}
Fraction sub(const Fraction& f1, const Fraction& f2)
{
int new_up = f1.up * f2.down - f2.up * f1.down;
int new_down = f1.down * f2.down;
return Fraction(new_up, new_down);
}
Fraction mul(const Fraction& f1, const Fraction& f2)
{
int new_up = f1.up * f2.up;
int new_down = f1.down * f2.down;
return Fraction(new_up, new_down);
}
Fraction div(const Fraction& f1, const Fraction& f2)
{
if (f2.up == 0)
{
cout<<"分母不能为0";
}
int new_up = f1.up * f2.down;
int new_down = f1.down * f2.up;
return Fraction(new_up, new_down);
}task4.cpp
查看代码
#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;
const 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：如果是友元函数：可以直接访问私有成员，但是破坏了封装性，可以用在重载非成员运算符
如果是自由函数：封装原则更加严格，可以用在类与类之间的运算
如果是命名空间加自由函数：可以避免全局命名的冲突，但是调用时要重复运用Fraction：：
如果是类加static：避免了友元带来的封装性破坏，但是仍然会更加复杂冗余
综合考虑我会选择类+static的方法
浙公网安备 33010602011771号