實驗任務1:
實驗程式碼：
1 #include <string> 2 3 // 類T: 宣告 4 class T { 5 // 物件屬性、方法 6 public: 7 T(int x = 0, int y = 0); // 普通建構函式 8 T(const T &t); // 複製建構函式 9 T(T &&t); // 移動建構函式 10 ~T(); // 解構函式 11 12 void adjust(int ratio); // 按係數成倍調整資料 13 void display() const; // 以(m1, m2)形式顯示T類物件資訊 14 15 private: 16 int m1, m2; 17 18 // 類屬性、方法 19 public: 20 static int get_cnt(); // 顯示當前T類物件總數 21 22 public: 23 static const std::string doc; // 類T的描述資訊 24 static const int max_cnt; // 類T物件上限 25 26 private: 27 static int cnt; // 當前T類物件數目 28 29 // 類T友元函式宣告 30 friend void func(); 31 }; 32 33 // 普通函式宣告 34 void func();
1 // 類T: 實現 2 // 普通函式實現 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成員資料類外初始化 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 // 物件方法 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 // 類方法 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 }
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 }
執行結果截圖：
問題1：
不能執行。
報錯截圖：
可能原因：
友元宣告在類內，定義在類外。如果不在類外進行普通函式宣告的話，那麼在task1.cpp進行編譯的時候，由於在類外無法訪問類內的私有成員，將找不到t.h中關於func 宣告。
問題2：
功能：
普通建構函式 T(int x = 0, int y = 0)：這是類的預設建構函式，用於初始化物件的成員變數 m1 和 m2。當建立類 T 的物件時，如果沒有提供特定的建構函式引數，將呼叫此建構函式。
複製建構函式 T(const T &t)：這個建構函式用於建立一個新物件，它是另一個同型別物件的副本。它透過複製已有物件的成員變數來初始化新物件。
移動建構函式 T(T &&t)：移動建構函式用於在不進行復制的情況下，將資源從一個物件轉移到另一個物件。它接受一個右值引用作為引數。
解構函式 ~T()：解構函式用於執行清理工作，釋放資源。
呼叫時機：
普通建構函式在物件建立時呼叫。
複製建構函式在物件透過另一個物件初始化時呼叫。
移動建構函式在物件透過另一個物件的移動初始化時呼叫。
解構函式在物件被銷燬時呼叫，例如當物件離開作用域或被顯式刪除時。
問題3：
不能。
因為靜態成員變數的定義和初始化應該在類定義之外進行，而不是在類定義內部。
實驗任務2：
實驗程式碼：
1 #pragma once 2 #include<iostream> 3 class Complex { 4 public: 5 static const std::string doc; 6 Complex(); 7 Complex(double x); 8 Complex(double x, double y); 9 Complex(const Complex& c); 10 double get_real()const; 11 double get_imag()const; 12 void add(const Complex& c); 13 friend Complex add(const Complex& c1, const Complex& c2); 14 15 friend bool is_equal(const Complex& c1, const Complex& c2); 16 17 friend bool is_not_equal(const Complex& c1, const Complex& c2); 18 19 friend void output(const Complex& c); 20 21 friend double abs(const Complex& c); 22 23 24 private: 25 double real; 26 double imag; 27 };
1 #include"complex.h" 2 #include<iostream> 3 #include<math.h> 4 const std::string Complex::doc = "a simplified complex class"; 5 Complex::Complex():real(0), imag(0) {} 6 Complex::Complex(double x) : real(x), imag(0) {} 7 Complex::Complex(double x, double y) : real(x), imag(y) {} 8 Complex::Complex(const Complex& c) : real(c.real), imag(c.imag) {} 9 double Complex::get_real() const { 10 11 return real; 12 13 } 14 double Complex::get_imag() const { 15 16 return imag; 17 18 } 19 void Complex::add(const Complex& other) { 20 21 real += other.real; 22 23 imag += other.imag; 24 25 } 26 Complex add(const Complex& c1, const Complex& c2) { 27 28 return Complex(c1.real + c2.real, c1.imag + c2.imag); 29 30 } 31 32 33 34 bool is_equal(const Complex& c1, const Complex& c2) { 35 36 return (c1.real == c2.real) && (c1.imag == c2.imag); 37 38 } 39 bool is_not_equal(const Complex& c1, const Complex& c2) 40 { 41 return !is_equal(c1, c2); 42 } 43 double abs(const Complex& c) { 44 45 return std::sqrt(c.real * c.real + c.imag * c.imag); 46 47 } 48 void output(const Complex& c) { 49 if (c.imag >= 0) { 50 std::cout << c.real << " + " << std::abs(c.imag) << "i"; 51 } 52 else 53 { 54 std::cout << c.real << " - " << std::abs(c.imag) << "i"; 55 } 56 57 }
#include"complex.h" #include <iostream> using std::cout; using std::endl; using std::boolalpha; void test() { cout << "類成員測試: " << endl; cout << Complex::doc << endl; cout << endl; cout << "Complex物件測試: " << endl; Complex c1; Complex c2(3, -4); const Complex c3(3.5); Complex c4(c3); 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 << "c4.real = " << c4.get_real() << ", c4.imag = " << c4.get_imag() << endl; cout << endl; cout << "複數運算測試: " << 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 != c3 : " << is_not_equal(c1, c3) << endl; c4 = add(c2, c3); cout << "c4 = c2 + c3, c4 = "; output(c4); cout << endl; } int main() { test(); }
執行結果截圖：
實驗任務3：
實驗程式碼：
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 << "標準庫模板類comple測試: " << 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 << "複數運算測試: " << 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 }
執行結果截圖：
問題：
介面：
complex<double> c1使用預設建構函式建立了一個複數物件c1
complex<double> c2(3, -4) 使用初始化列表構造複數物件c2
const complex<double> c3(3.5) 使用建構函式建立了一個常量複數物件c3
complex<double> c4(c3) 使用複製建構函式建立了複數物件c4
使用std::cout和<<運算子直接輸出複數物件
c4.real()和 c4.imag() 分別獲取複數物件的實部和虛部。
c1 += c2 使用+=運算子將c2加到c1上
(c1 == c2)使用==運算子比較兩個複數物件是否相等
(c1 != c3)使用!=運算子比較兩個複數物件是否不相等
abs(c2)計算複數物件c2的模;
c4 = c2 + c3使用+運算子將兩個複數物件相加
寫法更簡潔之處：
1.建構函式：
任務2：需要手動定義各種建構函式來初始化複數物件。
任務3：可以直接使用列表初始化或者提供特定的建構函式來建立複數物件，程式碼更為簡潔。
2.運算：
任務2：需要手動實現加法、減法、乘法和除法等運算子的過載。
任務3：標準庫complex類已經過載了基本的算術運算子，可以直接使用這些運算子進行復數運算。
3.訪問：
任務2：需要透過成員函式（如get_real()和get_imag()）來獲取實部和虛部。
任務3：可以直接使用.real()和.imag()成員函式來訪問複數的實部和虛部，程式碼更為直觀和簡潔。
4.輸出：
任務2：需要自定義一個output()函式來格式化輸出複數。
任務3：可以直接使用std::cout和<<運算子來輸出複數
5.模運算：
任務2：需要手動實現複數的模運算。
任務3：可以直接使用標準庫提供的abs()函式來計算複數的模。
啟發：標準庫complex類的介面設計簡潔直觀，易於理解和使用，可以使程式碼更加簡潔和直觀。
實驗任務4：
實驗程式碼：
1 #pragma once 2 #include <string> 3 4 class Fraction { 5 public: 6 Fraction(int up, int down = 1); 7 Fraction(const Fraction&); 8 9 int get_up() const; 10 int get_down() const; 11 Fraction negative() const; 12 int gcd()const; 13 friend Fraction add(const Fraction&, const Fraction&); 14 friend Fraction sub(const Fraction&, const Fraction&); 15 friend Fraction mul(const Fraction&, const Fraction&); 16 friend Fraction div(const Fraction&, const Fraction&); 17 friend void output(const Fraction&); 18 19 20 static const std::string doc; 21 22 private: 23 int up; 24 int down; 25 26 };
1 #include "Fraction.h" 2 #include <iostream> 3 #include<cmath> 4 const std::string Fraction::doc = "Fraction類v0.01版. 目前僅支援分數物件的構造、輸出、加/減/乘/除運算"; 5 6 Fraction::Fraction(int up, int down) : up(up), down(down) {} 7 8 Fraction::Fraction(const Fraction & other) : up(other.up), down(other.down) {} 9 10 int Fraction::get_up() const { 11 int a = gcd(); 12 return up/a; 13 14 } 15 16 int Fraction::get_down() const { 17 int a = gcd(); 18 return down/a; 19 20 } 21 22 Fraction Fraction::negative() const { 23 return Fraction(-up, down); 24 25 } 26 27 Fraction add(const Fraction & f1, const Fraction & f2) { 28 return Fraction(f1.up * f2.down + f2.up * f1.down, f1.down * f2.down); 29 30 } 31 32 Fraction sub(const Fraction & f1, const Fraction & f2) { 33 return Fraction(f1.up * f2.down - f2.up * f1.down, f1.down * f2.down); 34 35 } 36 37 Fraction mul(const Fraction & f1, const Fraction & f2) { 38 return Fraction(f1.up * f2.up, f1.down * f2.down); 39 40 } 41 42 Fraction div(const Fraction & f1, const Fraction & f2) { 43 return Fraction(f1.up * f2.down, f1.down * f2.up); 44 45 } 46 47 void output(const Fraction & f) { 48 int a = f.down, b = f.up; 49 int c = a, d = b; 50 int temp; 51 while (d != 0) 52 { 53 temp = c % d; 54 c = d; 55 d = temp; 56 } 57 int gcd = c; 58 b /= gcd; 59 a /= gcd; 60 if (a == 0) 61 { 62 std::cout << "分母不能為0"; 63 return; 64 } 65 if (a < 0) { 66 b = -b; 67 a = -a; 68 69 } 70 if (b == 0) { 71 std::cout << "0"; 72 73 } 74 else if (a == 1) { 75 std::cout << b; 76 77 } 78 else { 79 std::cout << b << "/" << a; 80 81 } 82 83 } 84 int Fraction::gcd()const 85 { 86 int c = up; 87 int d = down; 88 int temp; 89 while (d != 0) 90 { 91 temp = c % d; 92 c = d; 93 d = temp; 94 } 95 return c; 96 }
1 #include "Fraction.h" 2 #include <iostream> 3 4 using std::cout; 5 using std::endl; 6 7 8 void test1() { 9 cout << "Fraction類測試: " << 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 << "測試1: Fraction類基礎功能測試\n"; 40 test1(); 41 42 cout << "\n測試2: 分母為0測試: \n"; 43 test2(); 44 }
執行結果截圖：
實驗任務5：
實驗程式碼：
1 #ifndef _ _ACCOUNT_H_ _ 2 #define _ _ACCOUNT_H_ _ 3 class SavingsAccount{ 4 private: 5 int id; 6 double balance; 7 double rate; 8 int lastDate; 9 double accumulation; 10 static double total; 11 void record(int date,double amount); 12 double accumulate(int date)const{ 13 return accumulation+balance*(date-lastDate); 14 } 15 public: 16 SavingsAccount(int date,int id,double rate); 17 int getId()const{return id;} 18 double getBalance()const{return balance;} 19 double getRate()const{return rate;} 20 static double getTotal(){return total;} 21 void deposit(int date,double amount); 22 void withdraw(int date,double amount); 23 void settle(int date); 24 void show()const; 25 26 }; 27 #endif//_ _ACCOUNT_H_ _
1 #include"account.h" 2 #include<cmath> 3 #include<iostream> 4 using namespace std; 5 double SavingsAccount::total=0; 6 SavingsAccount::SavingsAccount(int date,int id,double rate) 7 :id(id),balance(0),rate(rate),lastDate(date),accumulation(0){ 8 cout<<date<<"\t#"<<id<<" is created"<<endl; 9 } 10 void SavingsAccount::record(int date,double amount){ 11 accumulation=accumulate(date); 12 lastDate=date; 13 amount=floor(amount*100+0.5)/100; 14 balance+=amount; 15 total+=amount; 16 cout<<date<<"\t#"<<id<<"\t"<<amount<<"\t"<<balance<<endl; 17 } 18 void SavingsAccount::deposit(int date,double amount){ 19 record(date,amount); 20 } 21 void SavingsAccount::withdraw(int date,double amount){ 22 if(amount>getBalance()) 23 cout<<"Error:not enough money"<<endl; 24 else 25 record(date,-amount); 26 } 27 void SavingsAccount::settle(int date){ 28 double interest=accumulate(date)*rate/365; 29 if(interest!=0) 30 record(date,interest); 31 accumulation=0; 32 } 33 void SavingsAccount::show()const{ 34 cout<<"#"<<id<<"\tBalance:"<<balance; 35 }
1 #include"account.h" 2 #include<iostream> 3 using namespace std; 4 int main() 5 { 6 SavingsAccount sa0(1,21325302,0.015); 7 SavingsAccount sa1(1,58320212,0.015); 8 sa0.deposit(5,5000); 9 sa1.deposit(25,10000); 10 sa0.deposit(45,5500); 11 sa1.withdraw(60,4000); 12 sa0.settle(90); 13 sa1.settle(90); 14 sa0.show();cout<<endl; 15 sa1.show();cout<<endl; 16 cout<<"Total:"<< SavingsAccount::getTotal()<<endl; 17 return 0; 18 }
可以在
accumulate() 和 getBalance() 加上 const 修飾符，可以防止資料被更改。可以在輸出時加一些提示語，可以讓輸出更直觀。
總結：
透過本次實驗，我明白了使用標準庫所帶來的簡潔，以及知道了怎麼透過多檔案的方式來編寫程式碼。