實驗2 類和物件_基礎程式設計1

實驗任務1:

實驗程式碼：

#include <string>

// 類T: 宣告
class T {
// 物件屬性、方法
public:
    T(int x = 0, int y = 0);   // 普通建構函式
    T(const T &t);  // 複製建構函式
    T(T &&t);       // 移動建構函式
    ~T();           // 解構函式

    void adjust(int ratio);      // 按係數成倍調整資料
    void display() const;           // 以(m1, m2)形式顯示T類物件資訊

private:
    int m1, m2;

// 類屬性、方法
public:
    static int get_cnt();          // 顯示當前T類物件總數

public:
    static const std::string doc;       // 類T的描述資訊
    static const int max_cnt;           // 類T物件上限

private:
    static int cnt;         // 當前T類物件數目

// 類T友元函式宣告
    friend void func();
};

// 普通函式宣告
void func();

// 類T: 實現
// 普通函式實現

#include "t.h"
#include <iostream>
#include <string>

using std::cout;
using std::endl;
using std::string;

// static成員資料類外初始化
const std::string T::doc{"a simple class sample"};
const int T::max_cnt = 999;
int T::cnt = 0;


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

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

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

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

void T::adjust(int ratio) {
    m1 *= ratio;
    m2 *= ratio;
}    

void T::display() const {
    cout << "(" << m1 << ", " << m2 << ")" ;
}     

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

// 友元
void func() {
    T t5(42);
    t5.m2 = 2049;
    cout << "t5 = "; t5.display(); cout << endl;
}

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

using std::cout;
using std::endl;

void test();

int main() {
    test();
    cout << "\nmain: \n";
    cout << "T objects'current count: " << T::get_cnt() << endl;
}

void test() {
    cout << "test class T: \n";
    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 << "t3 = "; t4.display(); cout << endl;

    cout << "T objects'current count: " << T::get_cnt() << endl;

    func();
}

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：

#pragma once
#include<iostream>
class Complex {
public:
    static const std::string doc;
    Complex();
    Complex(double x);
    Complex(double x, double y);
    Complex(const Complex& c);
    double get_real()const;
    double get_imag()const;
    void add(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);

    friend void output(const Complex& c);

    friend double abs(const Complex& c);


private:
    double real;
    double imag;
};

#include"complex.h"
#include<iostream>
#include<math.h>
const std::string Complex::doc = "a simplified complex class";
Complex::Complex():real(0), imag(0) {}
Complex::Complex(double x) : real(x), imag(0) {}
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& other) {

    real += other.real;

    imag += other.imag;

}
Complex add(const Complex& c1, const Complex& c2) {

    return Complex(c1.real + c2.real, c1.imag + c2.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);
}
double abs(const Complex& c) {

    return std::sqrt(c.real * c.real + c.imag * c.imag);

}
void output(const Complex& c) {
    if (c.imag >= 0) {
        std::cout << c.real << " + " << std::abs(c.imag) << "i";
    }
    else
    {
        std::cout << c.real << " - " << std::abs(c.imag) << "i";
    }

}

#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：

#include <iostream>
#include <complex>

using std::cout;
using std::endl;
using std::boolalpha;
using std::complex;

void test() {
    cout << "標準庫模板類comple測試: " << endl;
    complex<double> c1;
    complex<double> c2(3, -4);
    const complex<double> c3(3.5);
    complex<double> c4(c3);

    cout << "c1 = " << c1 << endl;
    cout << "c2 = " << c2 << endl;
    cout << "c3 = " << c3 << endl;
    cout << "c4 = " << c4 << endl;
    cout << "c4.real = " << c4.real() << ", c4.imag = " << c4.imag() << endl;
    cout << endl;

    cout << "複數運算測試: " << 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 != c3 : " << (c1 != c3) << endl;
    c4 = c2 + c3;
    cout << "c4 = c2 + c3, c4 = " << c4 << endl;
}

int main() {
    test();
}

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：

 #pragma once
 #include <string>

 class Fraction {
 public:
         Fraction(int up, int down = 1);
        Fraction(const Fraction&);
    
             int get_up() const;
         int get_down() const;
         Fraction negative() const;
         int gcd()const;
         friend Fraction add(const Fraction&, const Fraction&);
        friend Fraction sub(const Fraction&, const Fraction&);
         friend Fraction mul(const Fraction&, const Fraction&);
         friend Fraction div(const Fraction&, const Fraction&);
         friend void output(const Fraction&);
    
        
     static const std::string doc;
    
 private:
        int up;
         int down;
    
};

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

Fraction::Fraction(int up, int down) : up(up), down(down) {}

Fraction::Fraction(const Fraction & other) : up(other.up), down(other.down) {}

 int Fraction::get_up() const {
     int a = gcd();
         return up/a;
    
}

 int Fraction::get_down() const {
     int a = gcd();
     return down/a;
    
}

 Fraction Fraction::negative() const {
         return Fraction(-up, down);
    
}

 Fraction add(const Fraction & f1, const Fraction & f2) {
        return Fraction(f1.up * f2.down + f2.up * f1.down, f1.down * f2.down);
    
}

 Fraction sub(const Fraction & f1, const Fraction & f2) {
         return Fraction(f1.up * f2.down - f2.up * f1.down, f1.down * f2.down);
    
}

 Fraction mul(const Fraction & f1, const Fraction & f2) {
        return Fraction(f1.up * f2.up, f1.down * f2.down);
    
}

 Fraction div(const Fraction & f1, const Fraction & f2) {
         return Fraction(f1.up * f2.down, f1.down * f2.up);
    
}

 void output(const Fraction & f) {
         int a = f.down, b = f.up;
         int c = a, d = b;
         int temp;
         while (d != 0)
             {
                 temp = c % d;
                 c = d;
                 d = temp;
             }
         int gcd = c;
         b /= gcd;
         a /= gcd;
         if (a == 0)
         {
             std::cout << "分母不能為0";
             return;
         }
         if (a < 0) {
                 b = -b;
                 a = -a;
        
    }
         if (b == 0) {
                 std::cout << "0";
        
    }
    else if (a == 1) {
                 std::cout << b;
        
    }
    else {
                 std::cout << b << "/" << a;
        
    }
    
}
 int Fraction::gcd()const 
 {
     int c = up;
     int d = down;
     int temp;
     while (d != 0)
     {
         temp = c % d;
         c = d;
         d = temp;
     }
     return c;
 }

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

using std::cout;
using std::endl;


void test1() {
    cout << "Fraction類測試: " << 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() {
    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;
}

int main() {
    cout << "測試1: Fraction類基礎功能測試\n";
    test1();

    cout << "\n測試2: 分母為0測試: \n";
    test2();
}

執行結果截圖：

實驗任務5：

實驗程式碼：

#ifndef _ _ACCOUNT_H_ _
#define _ _ACCOUNT_H_ _
class SavingsAccount{
private:
    int id;
    double balance;
    double rate;
    int lastDate;
    double accumulation;
    static double total;
    void record(int date,double amount);
    double accumulate(int date)const{
        return accumulation+balance*(date-lastDate);
    }
public:
    SavingsAccount(int date,int id,double rate);
    int getId()const{return id;}
    double getBalance()const{return balance;}
    double getRate()const{return rate;}
    static double getTotal(){return total;}
    void deposit(int date,double amount);
    void withdraw(int date,double amount);
    void settle(int date);
    void show()const;
    
};
#endif//_ _ACCOUNT_H_ _

#include"account.h"
#include<cmath>
#include<iostream>
using namespace std;
double SavingsAccount::total=0;
SavingsAccount::SavingsAccount(int date,int id,double rate)
:id(id),balance(0),rate(rate),lastDate(date),accumulation(0){
    cout<<date<<"\t#"<<id<<" is created"<<endl;
} 
void  SavingsAccount::record(int date,double amount){
    accumulation=accumulate(date);
    lastDate=date;
    amount=floor(amount*100+0.5)/100;
    balance+=amount;
    total+=amount;
    cout<<date<<"\t#"<<id<<"\t"<<amount<<"\t"<<balance<<endl;
}
void  SavingsAccount::deposit(int date,double amount){
    record(date,amount);
}
void  SavingsAccount::withdraw(int date,double amount){
    if(amount>getBalance())
        cout<<"Error:not enough money"<<endl;
    else
        record(date,-amount);
}
void  SavingsAccount::settle(int date){
    double interest=accumulate(date)*rate/365;
    if(interest!=0)
        record(date,interest);
        accumulation=0;
}
void SavingsAccount::show()const{
    cout<<"#"<<id<<"\tBalance:"<<balance;
}

#include"account.h"
#include<iostream>
using namespace std;
int main()
{
     SavingsAccount sa0(1,21325302,0.015);
     SavingsAccount sa1(1,58320212,0.015);
     sa0.deposit(5,5000);
     sa1.deposit(25,10000);
     sa0.deposit(45,5500);
     sa1.withdraw(60,4000);
     sa0.settle(90);
     sa1.settle(90);
     sa0.show();cout<<endl;
     sa1.show();cout<<endl;
     cout<<"Total:"<< SavingsAccount::getTotal()<<endl;
     return 0;
}

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。