实验二
1.实验任务一
T.h代码如下
1 #pragma once 2 3 #include <string> 4 5 // 类T: 声明 6 class T { 7 // 对象属性、方法 8 public: 9 T(int x = 0, int y = 0); // 普通构造函数 10 T(const T &t); // 复制构造函数 11 T(T &&t); // 移动构造函数 12 ~T(); // 析构函数 13 14 void adjust(int ratio); // 按系数成倍调整数据 15 void display() const; // 以(m1, m2)形式显示T类对象信息 16 17 private: 18 int m1, m2; 19 20 // 类属性、方法 21 public: 22 static int get_cnt(); // 显示当前T类对象总数 23 24 public: 25 static const std::string doc; // 类T的描述信息 26 static const int max_cnt; // 类T对象上限 27 28 private: 29 static int cnt; // 当前T类对象数目 30 31 // 类T友元函数声明 32 friend void func(); 33 }; 34 35 // 普通函数声明 36 void func();
T.cpp代码如下
1 #include "T.h" 2 #include <iostream> 3 #include <string> 4 5 // 类T实现 6 7 // static成员数据类外初始化 8 const std::string T::doc{"a simple class sample"}; 9 const int T::max_cnt = 999; 10 int T::cnt = 0; 11 12 // 类方法 13 int T::get_cnt() { 14 return cnt; 15 } 16 17 // 对象方法 18 T::T(int x, int y): m1{x}, m2{y} { 19 ++cnt; 20 std::cout << "T constructor called.\n"; 21 } 22 23 T::T(const T &t): m1{t.m1}, m2{t.m2} { 24 ++cnt; 25 std::cout << "T copy constructor called.\n"; 26 } 27 28 T::T(T &&t): m1{t.m1}, m2{t.m2} { 29 ++cnt; 30 std::cout << "T move constructor called.\n"; 31 } 32 33 T::~T() { 34 --cnt; 35 std::cout << "T destructor called.\n"; 36 } 37 38 void T::adjust(int ratio) { 39 m1 *= ratio; 40 m2 *= ratio; 41 } 42 43 void T::display() const { 44 std::cout << "(" << m1 << ", " << m2 << ")" ; 45 } 46 47 // 普通函数实现 48 void func() { 49 T t5(42); 50 t5.m2 = 2049; 51 std::cout << "t5 = "; t5.display(); std::cout << '\n'; 52 }
task1.cpp代码如下
1 #include "T.h" 2 #include <iostream> 3 4 void test_T(); 5 6 int main() { 7 std::cout << "test Class T: \n"; 8 test_T(); 9 10 std::cout << "\ntest friend func: \n"; 11 func(); 12 } 13 14 void test_T() { 15 using std::cout; 16 using std::endl; 17 18 cout << "T info: " << T::doc << endl; 19 cout << "T objects'max count: " << T::max_cnt << endl; 20 cout << "T objects'current count: " << T::get_cnt() << endl << endl; 21 22 T t1; 23 cout << "t1 = "; t1.display(); cout << endl; 24 25 T t2(3, 4); 26 cout << "t2 = "; t2.display(); cout << endl; 27 28 T t3(t2); 29 t3.adjust(2); 30 cout << "t3 = "; t3.display(); cout << endl; 31 32 T t4(std::move(t2)); 33 cout << "t4 = "; t4.display(); cout << endl; 34 35 cout << "test: T objects'current count: " << T::get_cnt() << endl; 36 }
运行结果截图如下
问题1：程序无法正常运行，报错信息如下，显示func函数在前面没有声明，这是因为友元函数声明只是声明这个函数是友元函数，但函数本身还是要单独声明一下
问题2：T(int x = 0, int y = 0)是普通构造函数，功能是给m1,m2赋值，然后计数器cnt加1，被调用的时候显示“T constructor called”。当T对象没有参数，或者是有一个两个参数的时候调用；
T(const T &t)是复制构造函数，功能是复制已有对象的值给一个新的对象，计数器加1，被调用的时候显示“T copy constructor called”。当新的对象要复制已有对象值的时候调用；
T(T &&t)是移动构造函数，功能是将一个已有的T对象数据转移给新的这个对象，计数器加1，被调用时显示出“T move constructor called”。当要转移数据来初始化的时候调用；
~T()是析构函数，功能是释放对象在生命周期里占的内存，计数器减1，被调用时显示“T destructor called”。当对象的生命周期结束的时候调用。
问题3：无法正确编译，报错截图如下，报错原因是静态成员变量应该在类外初始化，把第八至第十行从T.cpp里面拿到T.h里面，不属于在类外定义和初始化，因此会报错。
2.实验任务二
Complex.h代码如下
1 #pragma once 2 #include <string> 3 4 class Complex{ 5 public: 6 static const std::string doc; 7 8 Complex(); 9 Complex(double r); 10 Complex(double r, double i); 11 Complex(const Complex &c); 12 13 double get_real() const; 14 double get_imag() const; 15 void add(const Complex &c); 16 17 friend void output(const Complex &c); 18 friend double abs(const Complex &c); 19 friend Complex add(const Complex &c1, const Complex &c2); 20 friend bool is_equal(const Complex &c1, const Complex &c2); 21 friend bool is_not_equal(const Complex &c1, const Complex &c2); 22 23 private: 24 double real, imag; 25 }; 26 void output(const Complex &c); 27 double abs(const Complex &c); 28 Complex add(const Complex &c1, const Complex &c2); 29 bool is_equal(const Complex &c1, const Complex &c2); 30 bool is_not_equal(const Complex &c1, const Complex &c2);
Complex.cpp代码如下
1 #include"Complex.h" 2 #include<cmath> 3 #include<iostream> 4 const std::string Complex::doc="a simplified complex class"; 5 Complex::Complex():real(0.0),imag(0.0){} 6 Complex::Complex(double r):real(r),imag(0.0){} 7 Complex::Complex(double r,double i):real(r),imag(i){} 8 Complex::Complex(const Complex&c):real(c.real),imag(c.imag){} 9 double Complex:: get_real() const 10 { 11 return real; 12 } 13 double Complex:: get_imag() const 14 { 15 return imag; 16 } 17 void Complex::add(const Complex&c) 18 { 19 real+=c.real; 20 imag+=c.imag; 21 } 22 void output(const Complex&c) 23 { 24 if(c.imag>=0) 25 { 26 std::cout<<c.real<<"+"<<c.imag<<"i"; 27 } 28 else 29 { 30 std::cout<<c.real<<"-"<<-c.imag<<"i"; 31 } 32 } 33 Complex add(const Complex&c1,const Complex&c2) 34 { 35 return Complex(c1.real+c2.real,c1.imag+c2.imag); 36 } 37 double abs(const Complex&c) 38 { 39 return sqrt(c.real*c.real+c.imag*c.imag); 40 } 41 bool is_equal(const Complex&c1,const Complex&c2) 42 { 43 return(c1.real==c2.real)&&(c1.imag==c2.imag); 44 } 45 bool is_not_equal(const Complex&c1,const Complex&c2) 46 { 47 return !is_equal(c1,c2); 48 }
task2代码如下
1 #include <iostream> 2 #include <iomanip> 3 #include <complex> 4 #include "Complex.h" 5 6 void test_Complex(); 7 void test_std_complex(); 8 9 int main() { 10 std::cout << "*******测试1: 自定义类Complex*******\n"; 11 test_Complex(); 12 13 std::cout << "\n*******测试2: 标准库模板类complex*******\n"; 14 test_std_complex(); 15 } 16 17 void test_Complex() { 18 using std::cout; 19 using std::endl; 20 using std::boolalpha; 21 22 cout << "类成员测试: " << endl; 23 cout << Complex::doc << endl 24 << endl; 25 26 cout << "Complex对象测试: " << endl; 27 Complex c1; 28 Complex c2(3, -4); 29 Complex c3(c2); 30 Complex c4 = c2; 31 const Complex c5(3.5); 32 33 cout << "c1 = "; output(c1); cout << endl; 34 cout << "c2 = "; output(c2); cout << endl; 35 cout << "c3 = "; output(c3); cout << endl; 36 cout << "c4 = "; output(c4); cout << endl; 37 cout << "c5.real = " << c5.get_real() 38 << ", c5.imag = " << c5.get_imag() << endl << endl; 39 40 cout << "复数运算测试: " << endl; 41 cout << "abs(c2) = " << abs(c2) << endl; 42 c1.add(c2); 43 cout << "c1 += c2, c1 = "; output(c1); cout << endl; 44 cout << boolalpha; 45 cout << "c1 == c2 : " << is_equal(c1, c2) << endl; 46 cout << "c1 != c2 : " << is_not_equal(c1, c2) << endl; 47 c4 = add(c2, c3); 48 cout << "c4 = c2 + c3, c4 = "; output(c4); cout << endl; 49 } 50 51 void test_std_complex() { 52 using std::cout; 53 using std::endl; 54 using std::boolalpha; 55 56 cout << "std::complex<double>对象测试: " << endl; 57 std::complex<double> c1; 58 std::complex<double> c2(3, -4); 59 std::complex<double> c3(c2); 60 std::complex<double> c4 = c2; 61 const std::complex<double> c5(3.5); 62 63 cout << "c1 = " << c1 << endl; 64 cout << "c2 = " << c2 << endl; 65 cout << "c3 = " << c3 << endl; 66 cout << "c4 = " << c4 << endl; 67 68 cout << "c5.real = " << c5.real() 69 << ", c5.imag = " << c5.imag() << endl << endl; 70 71 cout << "复数运算测试: " << endl; 72 cout << "abs(c2) = " << abs(c2) << endl; 73 c1 += c2; 74 cout << "c1 += c2, c1 = " << c1 << endl; 75 cout << boolalpha; 76 cout << "c1 == c2 : " << (c1 == c2)<< endl; 77 cout << "c1 != c2 : " << (c1 != c2) << endl; 78 c4 = c2 + c3; 79 cout << "c4 = c2 + c3, c4 = " << c4 << endl; 80 system("pause"); 81 }
运行截图如下
问题1：标准库模板类 complex 更简洁。有关联，因为标准库模板类 complex 使用了运算符重载
问题2：2-1 需要，因为abs，is_equal等函数需要用到复数的实部和虚部，实部和虚部是私有数据
2-2 经过查阅，std::complex 没有把 abs 设为友元
2-3 我觉得当需要访问私有数据的时候，需要用到friend
问题3：禁用=形式，想要实现Complex c4 = c2;那就不能让编译器调用拷贝构造函数，因此可以把拷贝构造函数设为private，这样就不会报错了
3.实验任务三
PlayerControl.h的代码如下
1 #pragma once 2 #include <string> 3 enum class ControlType {Play,Pause,Next,Prev,Stop,Unknown}; 4 class PlayerControl{ 5 private: 6 static int total_cnt; 7 public: 8 PlayerControl(); 9 static int get_cnt; 10 ControlType parse(const std::string& control_str); 11 void execute(ControlType cmd) const 12 };
PlayerControl.cpp代码如下
1 #include "PlayerControl.h" 2 #include <iostream> 3 #include <algorithm> 4 5 int PlayerControl::total_cnt = 0; 6 7 PlayerControl::PlayerControl() {} 8 9 ControlType PlayerControl::parse(const std::string &control_str) { 10 // 1. 将输入字符串转为小写，实现大小写不敏感 11 std::string lower_str; 12 for(auto &c:control_str){ 13 char ch=tolower(c); 14 lower_str+=ch; 15 } 16 // 2. 匹配"play"/"pause"/"next"/"prev"/"stop"并返回对应枚举 17 ControlType cmd=ControlType::Unknown; 18 if(lower_str=="play"){ 19 cmd=ControlType::Play; 20 total_cnt++; 21 }else if(lower_str=="pause"){ 22 cmd=ControlType::Pause; 23 total_cnt++; 24 }else if(lower_str=="next"){ 25 cmd=ControlType::Next; 26 total_cnt++; 27 }else if(lower_str=="prev"){ 28 cmd=ControlType::Prev; 29 total_cnt++; 30 }else if(lower_str=="stop"){ 31 cmd=ControlType::Stop; 32 total_cnt++; 33 }else{ 34 cmd=ControlType::Unknown; 35 } 36 return cmd; 37 } 38 39 40 void PlayerControl::execute(ControlType cmd) const { 41 switch (cmd) { 42 case ControlType::Play: std::cout << "[play] Playing music...\n"; break; 43 case ControlType::Pause: std::cout << "[Pause] Music paused\n"; break; 44 case ControlType::Next: std::cout << "[Next] Skipping to next track\n"; break; 45 case ControlType::Prev: std::cout << "[Prev] Back to previous track\n"; break; 46 case ControlType::Stop: std::cout << "[Stop] Music stopped\n"; break; 47 default: std::cout << "[Error] unknown control\n"; break; 48 } 49 } 50 51 int PlayerControl::get_cnt() { 52 return total_cnt; 53 }
task3.cpp代码如下
1 #include "PlayerControl.h" 2 #include <iostream> 3 4 void test() { 5 PlayerControl controller; 6 std::string control_str; 7 std::cout << "Enter Control: (play/pause/next/prev/stop/quit):\n"; 8 9 while(std::cin >> control_str) { 10 if(control_str == "quit") 11 break; 12 13 ControlType cmd = controller.parse(control_str); 14 controller.execute(cmd); 15 std::cout << "Current Player control: " << PlayerControl::get_cnt() << "\n\n"; 16 } 17 } 18 19 int main() { 20 test(); 21 }
运行结果截图如下
4.实验任务四
Fraction.h代码如下
1 #pragma once 2 #include <string> 3 4 class Fraction{ 5 private: 6 int up,down; 7 void simplify(); 8 public: 9 static const std::string doc; 10 Fraction(int up); 11 Fraction(int up,int down); 12 Fraction(const Fraction &f); 13 int get_up() const; 14 int get_down() const; 15 Fraction negative() const; 16 }; 17 //命名空间+自由函数 18 namespace FractionTool{ 19 void output(const Fraction &f); 20 Fraction add(const Fraction &f1,const Fraction &f2); 21 Fraction sub(const Fraction &f1,const Fraction &f2); 22 Fraction mul(const Fraction &f1,const Fraction &f2); 23 Fraction div(const Fraction &f1,const Fraction &f2); 24 }
Fraction.cpp代码如下
1 #include "Fraction.h" 2 #include<iostream> 3 #include<cstdlib> 4 const std::string Fraction::doc="Fraction类 v0.01版本，目前仅支持分数对象的构造、输出、加/减/乘/除运算"; 5 Fraction::Fraction(int up):up(up),down(1){} 6 Fraction::Fraction(int up,int down):up(up),down(down){ 7 simplify(); 8 } 9 Fraction::Fraction(const Fraction &f):up(f.up),down(f.down){ 10 simplify(); 11 } 12 int Fraction::get_up() const{ 13 return up; 14 } 15 int Fraction::get_down() const{ 16 return down; 17 } 18 Fraction Fraction::negative() const{ 19 return Fraction(-up,down); 20 } 21 22 int gcd(int a,int b){ 23 a=std::abs(a); 24 b=std::abs(b); 25 while(b!=0){ 26 int temp=b; 27 b=a%b; 28 a=temp; 29 } 30 return a; 31 } 32 33 void Fraction::simplify(){ 34 if(down<0){ 35 up=-up; 36 down=-down; 37 } 38 int gongyueshu=gcd(up,down); 39 if(gongyueshu!=0){ 40 up/=gongyueshu; 41 down/=gongyueshu; 42 } 43 } 44 namespace FractionTool{ 45 void output(const Fraction &f){ 46 if(f.get_down()==1){ 47 std::cout<<f.get_up(); 48 }else if(f.get_down()==0){ 49 std::cout<<"分母不能为0"; 50 }else if(f.get_up()==0){ 51 std::cout<<"0"; 52 } else{ 53 std::cout<<f.get_up()<<"/"<<f.get_down(); 54 } 55 } 56 Fraction add(const Fraction &f1,const Fraction &f2){ 57 int newup=f1.get_up()*f2.get_down()+f2.get_up()*f1.get_down(); 58 int newdown=f1.get_down()*f2.get_down(); 59 return Fraction(newup,newdown); 60 } 61 Fraction sub(const Fraction &f1,const Fraction &f2){ 62 int newup=f1.get_up()*f2.get_down()-f2.get_up()*f1.get_down(); 63 int newdown=f1.get_down()*f2.get_down(); 64 return Fraction(newup,newdown); 65 } 66 Fraction mul(const Fraction &f1,const Fraction &f2){ 67 int newup=f1.get_up()*f2.get_up(); 68 int newdown=f1.get_down()*f2.get_down(); 69 return Fraction(newup,newdown); 70 } 71 Fraction div(const Fraction &f1,const Fraction &f2){ 72 int newup=f1.get_up()*f2.get_down(); 73 int newdown=f1.get_down()*f2.get_up(); 74 return Fraction(newup,newdown); 75 } 76 }
task4.cpp代码如下
1 #include "Fraction.h" 2 #include <iostream> 3 4 void test1(); 5 void test2(); 6 7 int main() { 8 std::cout << "测试1: Fraction类基础功能测试\n"; 9 test1(); 10 11 std::cout << "\n测试2: 分母为0测试: \n"; 12 test2(); 13 } 14 15 void test1() { 16 using std::cout; 17 using std::endl; 18 using namespace FractionTool; 19 20 cout << "Fraction类测试: " << endl; 21 cout << Fraction::doc << endl << endl; 22 23 Fraction f1(5); 24 Fraction f2(3, -4), f3(-18, 12); 25 Fraction f4(f3); 26 cout << "f1 = "; output(f1); cout << endl; 27 cout << "f2 = "; output(f2); cout << endl; 28 cout << "f3 = "; output(f3); cout << endl; 29 cout << "f4 = "; output(f4); cout << endl; 30 31 const Fraction f5(f4.negative()); 32 cout << "f5 = "; output(f5); cout << endl; 33 cout << "f5.get_up() = " << f5.get_up() 34 << ", f5.get_down() = " << f5.get_down() << endl; 35 36 cout << "f1 + f2 = "; output(add(f1, f2)); cout << endl; 37 cout << "f1 - f2 = "; output(sub(f1, f2)); cout << endl; 38 cout << "f1 * f2 = "; output(mul(f1, f2)); cout << endl; 39 cout << "f1 / f2 = "; output(div(f1, f2)); cout << endl; 40 cout << "f4 + f5 = "; output(add(f4, f5)); cout << endl; 41 } 42 43 void test2() { 44 using std::cout; 45 using std::endl; 46 using namespace FractionTool; 47 48 Fraction f6(42, 55), f7(0, 3); 49 cout << "f6 = "; output(f6); cout << endl; 50 cout << "f7 = "; output(f7); cout << endl; 51 cout << "f6 / f7 = "; output(div(f6, f7)); cout << endl; 52 }
运行结果如下
问题：我选择的实现方式是命名空间+自由函数的形式，因为考虑到现在是Fraction类 v 0.01版，以后Fraction可能还要实现更多更加复杂的计算，那么到时候就可以在FractionTool里面直接添加函数即可，不用去修改Fraction类，更加方便，扩展性更强，并且我个人觉得用命名空间+自由函数的形式可以使代码看上去条理清晰，职责更加分明。
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