实验2 类和对象_基础编程1

实验任务1：

t.h源码：

#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源码：

// 类T: 实现
// 普通函数实现

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

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

// 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;


// 对象方法
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 << ")" ;
}     

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

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

task1.cpp源码：

#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();
}

运行测试结果截图：

问题1：

编译报错信息截图：

报错可能原因：当编译器编译这个项目时，会首先处理t.h头文件，然后处理t.cpp和task1.cpp源文件。在t.h中未对func()声明，即使在t,cpp中有func()函数，编译器并不会认为func()函数在主函数执行前便已对它进行声明。

 问题2：

　　普通构造函数：

　　　　功能：在对象进行创建时对其初始化参数。

　　　　调用时机：创建对象时。

　　复制构造函数：

　　　　功能：使用一个已经存在的对象，去初始化同类的一个新对象。

　　　　调用时机：(1)用类的一个对象去初始化该类的另一个对象时；(2)函数的形参时类的对象，调用函数时，进行形参和实参结合时；(3)函数的返回值时类的对象，函数执行完成返回调用者时。

　　移动构造函数：

　　　　功能：将一个对象的资源移动到新的对象中，而非复制。

　　　　调用时机：利用右值引用，通过移动而不复制实参的高性能方式构建新对象。

　　析构函数：

　　　　功能：完成对象被删除前的一些清理工作。

　　　　调用时机：在对象的生存期即将结束的时刻被自动调用的。

问题3：

不能正确编译运行。

 

实验任务2：

Complex.h源码：

#pragma once

#include<string>

class Complex
{
public:
    Complex(double r = 0, double i = 0);
    Complex(const Complex& c);
    ~Complex();

    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 double abs(const Complex& c);
    friend void output(const Complex& c);

private:
    double real, imag;
public:
    static const std::string doc;
};

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);
double abs(const Complex &c);
void output(const Complex &c);

Complex.cpp源码：

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

using namespace std;

const string Complex::doc{ "a simplified complex class" };

Complex::Complex(double r, double i)
{
    real = r;
    imag = i;
}
Complex::Complex(const Complex& c)
{
    real = c.real;
    imag = c.imag;
}
Complex::~Complex() = default;

double Complex::get_real() const
{
    return real;
}
double Complex::get_imag() const
{
    return imag;
}
void Complex::add(const Complex& c)
{
    real = real + c.real;
    imag = imag + c.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)
{
    if (c1.real == c2.real && c1.imag == c2.imag)
        return true;
    return false;
}
bool is_not_equal(const Complex& c1, const Complex& c2)
{
    if (c1.real == c2.real && c1.imag == c2.imag)
        return false;
    return true;
}
double abs(const Complex& c)
{
    return sqrt(c.real * c.real + c.imag * c.imag);
}
void output(const Complex& c)
{
    if(c.imag >= 0)
        cout << c.real << " + " << c.imag << "i";
    else
        cout << c.real << " - " << -c.imag << "i";
}

task2.cpp源码：

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

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

void test() {
    cout << "类成员测试: " << endl;
    cout << Complex::doc << endl;

    cout << endl;

    cout << "Complex对象测试: " << 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 << "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 != c3 : " << is_not_equal(c1, c3) << endl;
    c4 = add(c2, c3);
    cout << "c4 = c2 + c3, c4 = "; output(c4); cout << endl;
}

int main() {
    test();
}

运行测试结果截图：

 

实验任务3：

task3.cpp源码：

#include <iostream>
#include <complex>

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

void test() {
    cout << "标准库模板类comple测试: " << 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 << "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 != c3 : " << (c1 != c3) << endl;
    c4 = c2 + c3;
    cout << "c4 = c2 + c3, c4 = " << c4 << endl;
}

int main() {
    test();
}

运行测试结果截图：

 

实验任务4：

Fraction.h源码：

#pragma once
#include <string>

class Fraction
{
public:
    Fraction(int uu, int dd = 1);
    Fraction(const Fraction& f);
    ~Fraction();

    int get_up() const;
    int get_down() const;
    Fraction negative();

    Fraction simplify();

    friend void output(const Fraction& f1);
    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);
private:
    int up, down;
public:
    static const std::string doc;
};

void output(const Fraction& f1);
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);

Fraction.cpp源码：

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

using namespace std;

const std::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" };

Fraction::Fraction(int uu, int dd)
{
    up = uu;
    down = dd;
}
Fraction::Fraction(const Fraction& f)
{
    up = f.up;
    down = f.down;
}
Fraction::~Fraction() = default;

int Fraction::get_up() const
{
    return up;
}
int Fraction::get_down() const
{
    return down;
}
Fraction Fraction::negative()
{
    Fraction temp = simplify();
    return Fraction(-temp.up, temp.down);
}

Fraction Fraction::simplify()
{
    int small, uu, dd, pos_or_neg;
    if (up >= 0)
    {
        uu = up;
        if (down > 0)
        {
            dd = down;
            pos_or_neg = 1;
        }
        else
        {
            dd = -down;
            pos_or_neg = -1;
        }
    }
    else
    {
        uu = -up;
        if (down > 0)
        {
            dd = down;
            pos_or_neg = -1;
        }
        else
        {
            dd = -down;
            pos_or_neg = 1;
        }
    }
    if (uu > dd)
        small = dd;
    else
        small = uu;
    for (int i = small; i >= 1; i--)
        if (uu % i == 0 && dd % i == 0)
        {
            uu = uu / i;
            dd = dd / i;
            break;
        }
    if (pos_or_neg == 1)
        return Fraction(uu, dd);
    return Fraction(-uu, dd);
}

void output(const Fraction& f)
{
    Fraction temp = Fraction(f.up, f.down);
    temp = temp.simplify();
    if (temp.down == 0)
        cout << "分母不能为0";
    else
    {
        if (temp.up == 0)
            cout << "0";
        else if (temp.up != 0 && temp.down == 1)
            cout << temp.up;
        else
            cout << temp.up << "/" << temp.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);
}

task4.cpp源码：

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

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


void test1() {
    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;

    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 << "测试1: Fraction类基础功能测试\n";
    test1();

    cout << "\n测试2: 分母为0测试: \n";
    test2();
}

运行测试结果截图：

 

实验任务5：

 account.h源码：

#pragma once
#ifndef ACCOUNT_H
#define ACCOUNT_H
class SavingsAccount {
private:
    int id;                    //账号 
    double balance;            //余额
    double rate;            //存款的年利率 
    int lastDate;            //上次变更余额的时期 
    double accumulation;    //余额按日累加之和 
    static double total;     //所有账户的总金额
    //记录一笔账，date为日期，amount为金额，desc为说明
    void record(int date, double amount);
    //获得到指定日期为止的存款金额按日累积值
    double accumulate(int date) const {
        return accumulation + balance * (date - lastDate);
    }
public:
    //构造函数
    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);    //存入现金
    void withdraw(int date, double amount);    //取出现金
    //利息结算，每年1月1日调用一次该函数
    void settle(int date);
    //显示账户信息
    void show() const;
};
#endif //__ACCOUNT_H__

account.cpp源码：

#include"account.h"
#include<cmath>
#include<iostream>
using namespace std;

double SavingsAccount::total = 0;
//SavingsAccount类相关成员函数的实现
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;    //保留小数点后两位
    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;    //计算年息
    if (interest != 0)
        record(date, interest);
    accumulation = 0;
}
void SavingsAccount::show() const {
    cout << "#" << id << "\tBalance：" << balance;
}

5_11.cpp源码：

#include"account.h"
#include<iostream>
using namespace std;
int main() {
    //建立几个账户
    SavingsAccount sa0(1, 21325302, 0.015);
    SavingsAccount sa1(1, 58320212, 0.015);
    //几笔账目
    sa0.deposit(5, 5000);
    sa1.deposit(25, 10000);
    sa0.deposit(45, 5500);
    sa1.withdraw(60, 4000);
    //开户后第90天到了银行的计息日，结算所有账户的年息
    sa0.settle(90);
    sa1.settle(90);
    //输出各个账户信息
    sa0.show(); cout << endl;
    sa1.show(); cout << endl;
    cout << "Total：" << SavingsAccount::getTotal() << endl;
    return 0;
}

运行测试结果截图：

 分析：增加const关键字提高数据的安全性。使用静态数据成员total记录总金额，提高了使用性。

 

总结：

1.多文件结构的使用需要注意不同文件中操作的对象，如果对类的实现的文件修改，要注意是否在类的定义文件中同步。

2.const int返回类型 与 const成员函数 是两个不同的原型。

3.注意函数间相互调用，因为返回值类型不同导致的错误。