实验2 类和对象_基础编程1

实验任务1：

代码：

t.h

查看代码

 #pragma once
#include <string>
class T {
public:
    T(int x = 0, int y = 0); 
    T(const T &t);
    T(T &&t);
    ~T();
    void adjust(int ratio);
    void display() const;

private:
    int m1, m2;
public:
    static int get_cnt();
public:
    static const std::string doc;
    static const int max_cnt;

private:
    static int cnt;
    friend void func();
};

void func();

t.cpp

查看代码

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

using std::cout;
using std::endl;
using std::string;
const std::string T::doc{"a simple class sample"};
const int T::max_cnt = 999;
int T::cnt = 0;

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 << ")" ;
}     

int T::get_cnt() {
   return cnt;
}

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

task1.cpp

查看代码

  #include "t.h"
#include <iostream>
#include "t.cpp"
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();
}

运行结果：

问题1：

不能运行，报错为

可能是func不能访问T类的私有成员

 

问题2：

普通构造函数 T(int x = 0, int y = 0);
功能：创建 T 类对象，允许指定 m1 和 m2 的初始值
调用时机：参数创建对象

复制构造函数 T(const T &t);
功能：通过现有 T 类对象初始化新对象
调用时机：以现有对象初始化新对象

移动构造函数 T(T &&t);
功能：移动资源，减少不必要的拷贝
调用时机：使用 std::move 转换为右值引用

析构函数 ~T();
功能：执行清理操作
调用时机：程序结束时，调用析构函数

 

问题3：

不能，如果将静态成员变量的定义和初始化从t.cpp移动到t.h，会导致链接错误。

 

实验任务2：

代码：

Complex.h

查看代码

 #ifndef COMPLEX_H
#define COMPLEX_H

#include <iostream>
#include <cmath>

class Complex {
public:

    static const std::string doc;

    Complex();
    Complex(double real);
    Complex(double real, double imag);
    Complex(const Complex& other);

    double get_real() const;
    double get_imag() const;
    void add(const Complex& other);


    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;
};

#endif

Complex.cpp

查看代码

 #include "Complex.h"

const std::string Complex::doc = "a simplified complex class";

Complex::Complex() : real(0.0), imag(0.0) {}

Complex::Complex(double real) : real(real), imag(0.0) {}

Complex::Complex(double real, double imag) : real(real), imag(imag) {}

Complex::Complex(const Complex& other) : real(other.real), imag(other.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));
}

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

double abs(const Complex& c) {
    return std::sqrt(c.real * c.real + c.imag * c.imag);
}

task2.cpp

查看代码

 #include "Complex.h"
#include <iostream>
#include "Complex.cpp"
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();
}

运行结果：

 

实验任务3：

代码：

task3.cpp

查看代码

 #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();
}

运行结果：

默认构造函数:
complex<double> c1;

带实部和虚部的构造函数:
complex<double> c2(3, -4);

仅带实部的构造函数:
const complex<double> c3(3.5);

复制构造函数:
complex<double> c4(c3);

成员函数:
c4.real();

算术运算符重载:
c1 += c2;

比较运算符重载:
c1 == c2;

非成员函数:
abs(c2);

输出运算符重载:
cout << c1;

 

实验任务4：

代码：

Fraction.h

查看代码

 #ifndef FRACTION_H
#define FRACTION_H

#include <string>

class Fraction {
public:
    static const std::string doc;
    Fraction(int up = 0, int down = 1);
    Fraction(const Fraction &other);
    int get_up() const;
    int get_down() const;
    Fraction negative() const;

    friend void output(const Fraction &f);
    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;
    int down;

    void reduce(); 
};

#endif

Fraction.cpp

查看代码

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

using namespace std;
static int gcd(int a, int b) {
    return b == 0 ? a : gcd(b, a % b);
}
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.";

Fraction::Fraction(int up, int down) : up(up), down(down) {
    if (down < 0) {
        this->up = -this->up;
        this->down = -this->down;
    }
    reduce();
}

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

int Fraction::get_up() const {
    return up;
}

int Fraction::get_down() const {
    return down;
}

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

void Fraction::reduce() {
    int gcd_val = gcd(abs(up), abs(down));
    if (gcd_val != 0) {
        up /= gcd_val;
        down /= gcd_val;
    }
}

void output(const Fraction &f) {
    if (f.down == 1) {
        cout << f.up;
    } else {
        cout << f.up << "/" << f.down;
    }
}

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

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

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

Fraction div(const Fraction &f1, const Fraction &f2) {
    if (f2.up == 0) {
        cout << "分母不能为0" << endl;
        exit(1);
    }
    int numerator = f1.up * f2.down;
    int denominator = f1.down * f2.up;
    if (denominator < 0) {
        numerator = -numerator;
        denominator = -denominator;
    }
    return Fraction(numerator, denominator);
}

task4.cpp

查看代码

 #include "Fraction.h"
#include <iostream>
#include "Fraction.cpp"
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();
}

 

实验任务5：

代码：

account.h

查看代码

 #ifndef __ACCOUNT_H__
#define __ACCOUNT_H__

class SavingAccount{
private:
    int id;
    double balance;
    double rate;
    double lastData;
    double accumulation;

    static double total;

    void record(int data,double amount);
    double accumulate(int data) const
    {
        return accumulation+balance*(data-lastData);
    }
public:
    SavingAccount(int data,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 data,double amount);
    void withdraw(int data,double amount);
    void settle(int data);
    void show() const;
};
#endif

account.cpp

查看代码

 #include <bits/stdc++.h>
#include "account.h"
using namespace std;

double SavingAccount::total=0;
SavingAccount::SavingAccount(int data,int id,double rate)
    :id(id),balance(0),rate(rate),lastData(data),accumulation(0)
    {
        cout<<data<<"\t#"<<id<<" is created"<<endl;
    }

void SavingAccount::record(int data,double amount)
{
    accumulation=accumulate(data);
    lastData=data;
    amount=floor(amount*100+0.5)/100;
    balance+=amount;
    total+=amount;
    cout<<data<<"\t#"<<id<<"\t"<<amount<<"\t"<<balance<<endl;
}

void SavingAccount::deposit(int data,double amount)
{
    record(data,amount);
}

void SavingAccount::withdraw(int data,double amount)
{
    if (amount>getBalance())
        cout<<"Error:not enough money"<<endl;
    else
        record(data,-amount);
}

void SavingAccount::settle(int data)
{
    double interest=accumulate(data)*rate/365;
    if (interest!=0)
        record(data,interest);
    accumulation=0;
}
void SavingAccount::show() const
{
    cout<<"#"<<id<<"\tBalance:"<<balance;
}

task5.cpp

查看代码

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

int main ()
{
    SavingAccount sa0(1,21325302,0.015);
    SavingAccount sa1(1,58320212,0.015);

    sa0.deposit(5,5000);
    sa1.deposit(25,10000);
    sa0.deposit(45,5500);
    sa1.deposit(60,-4000);

    sa0.settle(90);
    sa1.settle(90);

    sa0.show();cout<<endl;
    sa1.show();cout<<endl;
    cout<<"Total:"<<SavingAccount::getTotal()<<endl;
    return 0;
}

实验结果：

代码合理

改进：
常量成员函数，所有不修改变量的成员都被声明为 const，有助于提高代码的安全性