实验2

任务一

t.h

 
#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();

task1.cpp

#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();
}

t.cpp

#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;
}

运行结果演示

问题1不能删除line36

原因：友元函数可以访问类的私有成员，但它依然是独立于类的函数。如果在类的实现中使用该函数，则需要为其提供普通函数的声明和定义。

报错信息：

问题2：

T(int x = 0, int y = 0);为普通构造函数。
功能: 用于初始化类的对象，可以带有默认参数。当创建对象时，如果没有提供任何参数，则使用默认值。

T(const T &t);为复制构造函数。
功能: 用于通过另一个同类对象来初始化一个新对象。用于对象的拷贝操作，例如在函数传参时传递对象，或者直接用一个对象初始化另一个对象。

T(T &&t);移动构造函数。
功能: 用于通过移动另一个同类对象来初始化一个新对象，通常用来优化性能。
调用时机:
当用一个右值对象初始化一个新对象时，例如 T obj2 = std::move(obj1);。
当返回一个对象的临时对象时，例如 T createObject() { return T(); }。

~T();析构函数。
功能: 用于清理对象所占用的资源，释放动态分配的内存。
调用时机:
当对象的生命周期结束时，即当对象超出其作用域时，如 T obj; 在函数结束时。
当对象通过 delete 被显式删除时，如 T *obj = new T(); delete obj;。
当栈上的对象超出作用域时，或者容器中的对象被移除时。

问题3

在C++11中，不能在头文件中直接初始化static成员变量。可以将其声明在头文件中，并在源文件中进行定义和初始化。

实验2

Complex.h

#ifndef COMPLEX_H
#define COMPLEX_H

#include <iostream>

class Complex {
private:
    double real;
    double imag;

public:

    Complex(double r = 0.0, double i = 0.0);
    Complex(const Complex &other);

    double get_real() const;
    double get_imag() const;


    void add(const Complex &other) ;

    friend bool is_equal(const Complex &other1 , const Complex &other2);
    friend bool is_not_equal(const Complex &other1 , const Complex &other2);

    friend Complex add(const Complex &other1 , const Complex &other2);
    friend void output(const Complex &other);
    friend double abs(const Complex &other);

    static char doc[40];
};

bool is_equal(const Complex &other1 , const Complex &other2);
bool is_not_equal(const Complex &other1 , const Complex &other2);

Complex add(const Complex &other1 , const Complex &other2);
void output(const Complex &other);
double abs(const Complex &other);

#endif

Complex.cpp

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

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

double Complex::get_real() const {
    return real;
}

double Complex::get_imag() const {
    return imag;
}

Complex::Complex(const Complex &other){
    real = other.get_real();
    imag = other.get_imag();
}

void Complex::add(const Complex& other){
   real += other.real;
   imag += other.imag;

   return ;
}

double abs(const Complex& other){

    double sum;
    sum = other.imag * other.imag + other.real * other.real;
    double ave = sqrt(sum);
    return ave;
}

bool is_equal(const Complex& other1 , const Complex& other2){
    if(other1.get_imag() == other2.get_imag() && other1.get_real() == other2.get_real()){
        return true;
    }

    else
        return false;
}

bool is_not_equal(const Complex& other1 , const Complex& other2){
    if(other1.get_imag() == other2.get_imag() && other1.get_real() == other2.get_real()){
        return false;
    }

    else
        return true;
}

Complex add(const Complex& other1 , const Complex& other2){
    return Complex(other1.get_real() + other2.get_real() , other1.get_imag() + other2.get_imag());
}

void output(const Complex& other){
    std::cout << other.get_real();
    double imagy;
    if(other.get_imag() < 0){
        std::cout << " - ";
        imagy = (-1.0) * other.get_imag();
    }
    else{
        std::cout << " + ";
        imagy = other.get_imag();
    }
    std::cout << imagy << 'i';


    return;
}

char Complex::doc[40] = {"a simplified Complex class"};

task2.cpp

#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();
}

 

任务3

#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();
}

任务4

function.h

#pragma once
#include <string>

class Fraction {
public:
    // 类的描述信息
    static const std::string doc;
    // 构造函数
    Fraction(int up = 0, int down = 1);
    Fraction(const Fraction& f);
    // 接口函数
    int get_up() const;
    int get_down() const;
    Fraction negative() const;
    // 友元函数声明
    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;
};

function.cpp

#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();
    return 0;
}

任务5

account.h

#include<iostream>

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 rate,double amount);
    void withdraw(int rate,double amount);
    void settle(int date);
    void show() const;

};

account.cpp

#include "account.h"
#include<cmath>
#include<iostream>

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

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<<"Erroe: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;
}

task5

#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;
}