task 1
代码：
t.h
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
1 // 类T: 实现 2 // 普通函数实现 3 4 #include "t.h" 5 #include <iostream> 6 #include <string> 7 8 using std::cout; 9 using std::endl; 10 using std::string; 11 12 // static成员数据类外初始化 13 const std::string T::doc{"a simple class sample"}; 14 const int T::max_cnt = 999; 15 int T::cnt = 0; 16 17 18 // 对象方法 19 T::T(int x, int y): m1{x}, m2{y} { 20 ++cnt; 21 cout << "T constructor called.\n"; 22 } 23 24 T::T(const T &t): m1{t.m1}, m2{t.m2} { 25 ++cnt; 26 cout << "T copy constructor called.\n"; 27 } 28 29 T::T(T &&t): m1{t.m1}, m2{t.m2} { 30 ++cnt; 31 cout << "T move constructor called.\n"; 32 } 33 34 T::~T() { 35 --cnt; 36 cout << "T destructor called.\n"; 37 } 38 39 void T::adjust(int ratio) { 40 m1 *= ratio; 41 m2 *= ratio; 42 } 43 44 void T::display() const { 45 cout << "(" << m1 << ", " << m2 << ")" ; 46 } 47 48 // 类方法 49 int T::get_cnt() { 50 return cnt; 51 } 52 53 // 友元 54 void func() { 55 T t5(42); 56 t5.m2 = 2049; 57 cout << "t5 = "; t5.display(); cout << endl; 58 }
task1.cpp
1 #include "t.h" 2 #include <iostream> 3 4 using std::cout; 5 using std::endl; 6 7 void test(); 8 9 int main() { 10 test(); 11 cout << "\nmain: \n"; 12 cout << "T objects'current count: " << T::get_cnt() << endl; 13 } 14 15 void test() { 16 cout << "test class T: \n"; 17 cout << "T info: " << T::doc << endl; 18 cout << "T objects'max count: " << T::max_cnt << endl; 19 cout << "T objects'current count: " << T::get_cnt() << endl << endl; 20 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 << "t3 = "; t4.display(); cout << endl; 34 35 cout << "T objects'current count: " << T::get_cnt() << endl; 36 37 func(); 38 }
运行结果截图：
回答问题：
问题1：
答：func()函数需要在类外声明，不然就会显示func()函数没有定义。
问题2：
答：
普通构造函数T(int x = 0, int y = 0)，传入两个参数x，y来创建一个实例，并且x,y在默认情况下都是0。
复制构造函数T(const T& t)，传入参数是一个已经存在的对象，会复制这个已有对象的x,y来创建一个新的对象。
移动构造函数T(T &&t)，右值引用，将已经存在对象的x,y移动过来创建一个新的对象，并且原对象不再拥有原来的x,y。
构造函数在每次对象的创建时会调用，根据不同答参数传入和预期功能，分别调用合适的构造函数，特别的，复制构造函数在对象作为函数参数传递时也会调用。析构函数在每个对象生命周期结束时会被调用。
问题3：
答：不能正确编译运行
task2
代码：
Complex.h
1 #pragma once 2 #include <string> 3 4 using std::string; 5 6 class Complex { 7 public: 8 Complex(); 9 Complex(double r, double i = 0); 10 Complex(const Complex& c); 11 12 double get_real() const; 13 double get_imag() const; 14 void add(const Complex& c); 15 16 friend Complex add(const Complex& c1, const Complex& c2); 17 friend bool is_equal(const Complex& c1, const Complex& c2); 18 friend bool is_not_equal(const Complex& c1, const Complex& c2); 19 friend void output(const Complex& c); 20 friend double abs(const Complex& c); 21 22 private: 23 double real, imag; 24 25 public: 26 static const string doc; 27 };
Complex.cpp
1 #include <iostream> 2 #include "Complex.h" 3 4 using std::string; 5 using std::cout; 6 using std::endl; 7 8 const string Complex::doc{ "a simplified complex class" }; 9 10 Complex::Complex():real{0}, imag{0}{} 11 Complex::Complex(double r, double i): real{r}, imag{i}{} 12 Complex::Complex(const Complex& c):real{c.real}, imag{c.imag}{} 13 14 double Complex::get_real() const { return real; } 15 double Complex::get_imag() const { return imag; } 16 void Complex::add(const Complex& c) { 17 real += c.real; 18 imag += c.imag; 19 } 20 21 Complex add(const Complex& c1, const Complex& c2) { 22 Complex c3; 23 c3.real = c1.real + c2.real; 24 c3.imag = c1.imag + c2.imag; 25 return c3; 26 } 27 28 bool is_equal(const Complex& c1, const Complex& c2) { 29 if (c1.real == c2.real && c1.imag == c2.imag) 30 return true; 31 else 32 return false; 33 } 34 35 bool is_not_equal(const Complex& c1, const Complex& c2) { 36 if (c1.real == c2.real && c1.imag == c2.real) 37 return false; 38 else 39 return true; 40 } 41 42 void output(const Complex& c) { 43 cout << c.real; 44 if (c.imag >= 0) 45 cout << " + " << c.imag << "i" << endl; 46 else 47 cout << " - " << abs(c.imag) << "i" << endl; 48 49 50 } 51 52 double abs(const Complex& c) { 53 return sqrt(c.real * c.real + c.imag * c.imag); 54 }
task2.cpp
1 #include "Complex.h" 2 #include <iostream> 3 4 using std::cout; 5 using std::endl; 6 using std::boolalpha; 7 8 void test() { 9 cout << "类成员测试: " << endl; 10 cout << Complex::doc << endl; 11 12 cout << endl; 13 14 cout << "Complex对象测试: " << endl; 15 Complex c1; 16 Complex c2(3, -4); 17 const Complex c3(3.5); 18 Complex c4(c3); 19 20 cout << "c1 = "; output(c1); cout << endl; 21 cout << "c2 = "; output(c2); cout << endl; 22 cout << "c3 = "; output(c3); cout << endl; 23 cout << "c4 = "; output(c4); cout << endl; 24 cout << "c4.real = " << c4.get_real() << ", c4.imag = " << c4.get_imag() << endl; 25 26 cout << endl; 27 28 cout << "复数运算测试: " << endl; 29 cout << "abs(c2) = " << abs(c2) << endl; 30 c1.add(c2); 31 cout << "c1 += c2, c1 = "; output(c1); cout << endl; 32 cout << boolalpha; 33 cout << "c1 == c2 : " << is_equal(c1, c2) << endl; 34 cout << "c1 != c3 : " << is_not_equal(c1, c3) << endl; 35 c4 = add(c2, c3); 36 cout << "c4 = c2 + c3, c4 = "; output(c4); cout << endl; 37 } 38 39 int main() { 40 test(); 41 }
运行结果截图：
task3
代码：
1 #include <iostream> 2 #include <complex> 3 4 using std::cout; 5 using std::endl; 6 using std::boolalpha; 7 using std::complex; 8 9 void test() { 10 cout << "标准库模板类comple测试: " << endl; 11 complex<double> c1; 12 complex<double> c2(3, -4); 13 const complex<double> c3(3.5); 14 complex<double> c4(c3); 15 16 cout << "c1 = " << c1 << endl; 17 cout << "c2 = " << c2 << endl; 18 cout << "c3 = " << c3 << endl; 19 cout << "c4 = " << c4 << endl; 20 cout << "c4.real = " << c4.real() << ", c4.imag = " << c4.imag() << endl; 21 cout << endl; 22 23 cout << "复数运算测试: " << endl; 24 cout << "abs(c2) = " << abs(c2) << endl; 25 c1 += c2; 26 cout << "c1 += c2, c1 = " << c1 << endl; 27 cout << boolalpha; 28 cout << "c1 == c2 : " << (c1 == c2) << endl; 29 cout << "c1 != c3 : " << (c1 != c3) << endl; 30 c4 = c2 + c3; 31 cout << "c4 = c2 + c3, c4 = " << c4 << endl; 32 } 33 34 int main() { 35 test(); 36 }
测试结果截图：
回答问题：
问题1：
答：在输出复数时能直接cout，而不用调用output()函数；在进行+=、+等运算时，能够像普通数字运算那样直接进行；在判断是否相等时，也能够用==、!=来判断。
问题2：
答：标准库complex模板类大大方便了使用复数时的操作。不过同样的功能，我们也可以在自定义类里通过操作函数来实现。
task4
代码：
Fraction.h
1 #pragma 2 #include<string> 3 4 using namespace std; 5 6 class Fraction { 7 public: 8 Fraction(int u, int d = 1); 9 Fraction(const Fraction & f); 10 11 int get_up() const; 12 int get_down() const; 13 Fraction negative() const; 14 15 private: 16 int up, down; 17 18 public: 19 static const string doc; 20 21 friend void output(const Fraction f); 22 friend Fraction add(const Fraction f1, const Fraction f2); 23 friend Fraction sub(const Fraction f1, const Fraction f2); 24 friend Fraction mul(const Fraction f1, const Fraction f2); 25 friend Fraction div(const Fraction f1, const Fraction f2); 26 27 }; 28 29 void output(const Fraction f); 30 Fraction add(const Fraction f1, const Fraction f2); 31 Fraction sub(const Fraction f1, const Fraction f2); 32 Fraction mul(const Fraction f1, const Fraction f2); 33 Fraction div(const Fraction f1, const Fraction f2);
Fraction.cpp
1 #include<iostream> 2 #include<string> 3 #include"Fraction.h" 4 5 using namespace std; 6 7 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.\n" }; 8 9 Fraction::Fraction(int u, int d) { 10 int i = 1; 11 if (u < 0) 12 i = -i; 13 if (d < 0) 14 i = -i; 15 16 int p = abs(u); 17 int q = abs(d); 18 if (u != 0 && d != 0) { 19 int a = max(p, q); 20 int b = min(p, q); 21 int r = a % b; 22 while (r != 0) { 23 a = b; 24 b = r; 25 r = a % b; 26 } 27 28 up = i * p / b; 29 down = q / b; 30 31 } 32 else { 33 up = u; 34 down = d; 35 } 36 } 37 Fraction::Fraction(const Fraction & f) : up{ f.up }, down{ f.down } {} 38 39 int Fraction::get_up() const { 40 return up; 41 } 42 int Fraction::get_down() const { 43 return down; 44 } 45 Fraction Fraction::negative() const { 46 Fraction f(1); 47 f.up = -up; 48 f.down = down; 49 return f; 50 } 51 52 //最大公因数 53 int func(int x, int y) { 54 if (x == 0 || y == 0) 55 return 1; 56 int a = max(x, y); 57 int b = min(x, y); 58 int r = a % b; 59 while(r != 0){ 60 a = b; 61 b = r; 62 r = a % b; 63 } 64 65 return b; 66 } 67 68 void output(Fraction f) { 69 int t = func(abs(f.up), abs(f.down)); 70 int up = abs(f.up) / t; 71 int down = abs(f.down) / t; 72 73 if (f.down == 0) 74 cout << "分母不能为0" << endl; 75 else if (f.up == 0) 76 cout << "0" << endl; 77 else if (f.down == 1) 78 cout << f.up << endl; 79 else { 80 if ((f.up < 0 && f.down > 0) || (f.up > 0 && f.down < 0)) 81 cout << "-"; 82 cout << up << "/" << down << endl; 83 } 84 85 } 86 87 Fraction add(const Fraction f1, const Fraction f2) { 88 Fraction f(1); 89 f.down = f1.down * f2.down / func(f1.down, f2.down); 90 f.up = f1.up * f.down / f1.down + f2.up * f.down / f2.down; 91 return f; 92 } 93 94 Fraction sub(const Fraction f1, const Fraction f2) { 95 Fraction f(1); 96 f.down = f1.down * f2.down / func(f1.down, f2.down); 97 f.up = f1.up * f.down / f1.down - f2.up * f.down / f2.down; 98 return f; 99 } 100 101 Fraction mul(const Fraction f1, const Fraction f2) { 102 Fraction f(1); 103 f.up = f1.up * f2.up; 104 f.down = f1.down * f2.down; 105 return f; 106 } 107 108 Fraction div(const Fraction f1, const Fraction f2) { 109 Fraction f(1); 110 if (f2.up == 0 || f2.down == 0) 111 f.up = f.down = 0; 112 else { 113 f.up = f1.up * f2.down; 114 f.down = f1.down * f2.up; 115 } 116 return f; 117 }
task4.cpp
1 #include "Fraction.h" 2 #include <iostream> 3 4 using std::cout; 5 using std::endl; 6 7 8 void test1() { 9 cout << "Fraction类测试: " << endl; 10 cout << Fraction::doc << endl << endl; 11 12 Fraction f1(5); 13 Fraction f2(3, -4), f3(-18, 12); 14 Fraction f4(f3); 15 cout << "f1 = "; output(f1); cout << endl; 16 cout << "f2 = "; output(f2); cout << endl; 17 cout << "f3 = "; output(f3); cout << endl; 18 cout << "f4 = "; output(f4); cout << endl; 19 20 Fraction f5(f4.negative()); 21 cout << "f5 = "; output(f5); cout << endl; 22 cout << "f5.get_up() = " << f5.get_up() << ", f5.get_down() = " << f5.get_down() << endl; 23 24 cout << "f1 + f2 = "; output(add(f1, f2)); cout << endl; 25 cout << "f1 - f2 = "; output(sub(f1, f2)); cout << endl; 26 cout << "f1 * f2 = "; output(mul(f1, f2)); cout << endl; 27 cout << "f1 / f2 = "; output(div(f1, f2)); cout << endl; 28 cout << "f4 + f5 = "; output(add(f4, f5)); cout << endl; 29 } 30 31 void test2() { 32 Fraction f6(42, 55), f7(0, 3); 33 cout << "f6 = "; output(f6); cout << endl; 34 cout << "f7 = "; output(f7); cout << endl; 35 cout << "f6 / f7 = "; output(div(f6, f7)); cout << endl; 36 } 37 38 int main() { 39 cout << "测试1: Fraction类基础功能测试\n"; 40 test1(); 41 42 cout << "\n测试2: 分母为0测试: \n"; 43 test2(); 44 }
运行结果截图：
task5
代码：
account.h
1 #pragma once 2 3 class SavingAccount { 4 private: 5 int id; 6 double balance; 7 double rate; 8 int lastDate; 9 double accumulation; 10 11 static double total; 12 13 void record(int date, double amount); 14 15 double accumulate(int date) const { 16 return accumulation + balance * (date - lastDate); 17 } 18 19 public: 20 SavingAccount(int date, int id, double rate); 21 22 int getId() const { return id; } 23 double getBalance() const { return balance; } 24 double getRate() const { return rate; } 25 26 static double getTotal() { return total; } 27 28 void deposit(int date, double amount); 29 void withdraw(int date, double amount); 30 void settle(int date); 31 void show() const; 32 33 };
account.cpp
1 #include"account.h" 2 #include<iostream> 3 #include<cmath> 4 5 using namespace std; 6 7 double SavingAccount::total = 0; 8 9 SavingAccount::SavingAccount(int date, int id, double rate) 10 : id(id), balance(0), rate(rate), lastDate(date), accumulation(0) { 11 cout << date << "\t#" << id << "is created" << endl; 12 } 13 14 void SavingAccount::record(int date, double amount) { 15 accumulation = accumulate(date); 16 lastDate = date; 17 amount = floor(amount * 100 + 0.5) / 100; 18 balance += amount; 19 total += amount; 20 cout << date << "\t#" << id << "\t" << amount << "\t" << balance << endl; 21 } 22 23 void SavingAccount::deposit(int date, double amount) { 24 record(date, amount); 25 } 26 27 void SavingAccount::withdraw(int date, double amount) { 28 if (amount > getBalance()) 29 cout << "Error: not enough money" << endl; 30 else 31 record(date, -amount); 32 } 33 34 void SavingAccount::settle(int date) { 35 double interest = accumulate(date) * rate / 365; 36 if (interest != 0) 37 record(date, interest); 38 accumulation = 0; 39 } 40 41 void SavingAccount::show() const { 42 cout << "#" << id << "\tBalance: " << balance; 43 }
5_11.cpp
1 #include "account.h" 2 #include <iostream> 3 4 using namespace std; 5 6 int main() { 7 SavingAccount sa0(1, 21325302, 0.015); 8 SavingAccount sa1(1, 58320212, 0.015); 9 10 sa0.deposit(5, 5000); 11 sa1.deposit(25, 10000); 12 sa0.deposit(45, 5500); 13 sa1.withdraw(60, 4000); 14 15 sa0.settle(90); 16 sa1.settle(90); 17 18 sa0.show(); cout << endl; 19 sa1.show(); cout << endl; 20 cout << "Total: " << SavingAccount::getTotal() << endl; 21 22 }
运行结果截图：
回答问题：
合理，有疑问：计算完年息之后accumulation为什么要重置为0？
