实验2 类和对象_基础编程1

实验任务一

源码

#pragma once

#include<string>

class T {
public:
    T(int x = 0, int y = 0);
    T(const T& t);
    T(T&& t);//移动构造函数
    ~T();
    void adjust(int ratio);//按系数成倍调整数据
    void display()const;//以（m1,m2)形式显示对象信息

private:
    int m1, m2;

public:
    static int get_cnt();//显示对象总数

public:
    static const std::string doc;//描述信息
    static const int max_cnt;//对象上限

private:
    static int cnt;//对象数目
    friend void func();
};

void func();

#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;
}

#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 << "t4 = "; t4.display(); cout << endl;

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

    func();
}

运行结果

问题一：

 如果func()没有被调用，并且没有其他地方依赖于它的实现，那么从项目中移除func()的定义或调用通常不会影响编译和运行。然而，如果func()的声明（作为友元）被保留，但实现被移除，并且其他代码（如测试代码或未来的开发）试图调用func()，那么这将导致链接错误，因为找不到func()的实现。

问题二：

1.T(int x = 0, int y = 0);为带有默认参数的默认构造函数。

    功能：当创建对象时没有提供任何初始化参数时，使用此构造函数。它允许对象以某种默认状态被创建。

    调用时机：在创建对象时，如果没有提供足够的参数来匹配其他构造函数，则调用默认构造函数。

2.T(const T& t);为拷贝构造函数。

    功能：用于创建一个新对象，作为另一个同类型对象的副本。它接受一个对同类型对象的常量引用作为参数。

    调用时机：当使用另一个同类型对象初始化新对象时（如T obj2 = obj1;）；

                      当对象作为函数参数按值传递时；

                       当对象从函数按值返回时。

3.T(T&& t);为移动构造函数。

    功能：从t中窃取资源并初始化新对象，为避免不必要的资源复制

    调用时机：当使用std::move显式地将对象转换为右值，并用于初始化新对象时。

4.~T();为析构函数。

    功能：析构函数在对象生命周期结束时自动调用，用于执行清理操作，如释放对象占用的资源（如动态分配的内存、文件句柄等）。

    调用时机：当对象的生命周期结束时，如离开作用域（对于局部变量）、被删除（对于动态分配的对象）、或容器（如std::vector）被销毁且包含该类型的对象时。

问题三：

不行

 

 

实验任务二

 源码

#pragma once

#include<string>

class Complex {
public:
    static const std::string doc;
private:
    double real; double imag;
public:
    Complex(double r = 0, double i = 0);
    Complex(const Complex& c);

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

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

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

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

Complex::Complex(double r,double i):real{r},imag{i}{}
Complex::Complex(const Complex& comp) :real{ comp.real }, imag{ comp.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) {
    if (c1.real == c2.real)
        if (c1.imag == c2.imag)
            return true;
    return false;
}

bool is_not_equal(const Complex& c1, const Complex& c2) {
    if (c1.real == c2.real)
        if (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) {
    cout << c.real << "+" << c.imag;
}

#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();
}

运行结果

 

 

实验任务三

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complex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

 思考：

1.提供了：构造函数（能自定义对象类型），取模，比较

2.可以提供接口自定义对象类型

 

 

实验任务四

源码

#pragma once
#include<iostream>
#include<string>
#include<algorithm>

class Fraction {
private:
    int up;
    int down;
public:
    static const std::string doc;

    Fraction(int u = 0, int d = 1);
    Fraction(const Fraction& other);

    int get_up() const;
    int get_down() const;

    Fraction negative() const;

    friend void simplify(Fraction&f);

    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);

};

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


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 u, int d) :up(u), down(d) { simplify(*this); };
//用this指针
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;
}

//求负分数
Fraction Fraction:: negative() const{
    return Fraction(-up, -down);
}

void simplify(Fraction& f) {
    //化简，先求最大公约数
    int a = f.up, b = f.down;
    int temp;
    while (b != 0) {
        temp = b;
        b = a % b;
        a = temp;
    }
    int gcd = a;//最大公约数
    f.up /= gcd;
    f.down /= gcd;

    //确保分母为正
    if (f.down < 0) {
        f.up = -f.up;
        f.down = -f.down;
    }
}

//输出分数
void output(const Fraction& f) {
    if (f.down == 0)return;
    if (f.down == 1) {
        std::cout << f.up << std::endl;
        return;
    }
    std::cout << (f.up<0?"-" :"") <<std::abs(f.up)<< "/" << f.down << std::endl;
}

//分数加法
Fraction add(const Fraction& f1, const Fraction& f2) {
    Fraction result;
    result.up = f1.up * f2.down + f2.up * f1.down;
    result.down = f1.down * f2.down;
    simplify(result);
    return result;
}

//分数减法
Fraction sub(const Fraction& f1, const Fraction& f2) {
    Fraction result(f1.up * f2.down - f2.up * f1.down, f1.down * f2.down);
    simplify(result);
    return result;
}

//分数乘法
Fraction mul(const Fraction& f1, const Fraction& f2) {
    Fraction result(f1.up * f2.up, f1.down * f2.down);
    simplify(result);
    return result;
}

//分数除法
Fraction div(const Fraction& f1, const Fraction& f2) {
    if (f2.up == 0) {
        std::cout<<"分母不能为0"<<std::endl;
        return Fraction(0,0);
    }
    Fraction result;
    result.up = f1.up * f2.down; // 分子相乘（f1的分子乘以f2的分母）
    result.down = f1.down * f2.up; // 分母相乘（f1的分母乘以f2的“分子”，但f2的分子在这里视为其倒数的分母部分）
    simplify(result); // 化简
    return result;
}

#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();
}

运行结果

 

 

实验任务五

源码

#pragma once
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;
};

#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;
}

运行结果