实验2 类和对象_基础编程1

任务1：

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();

 

 

 

t.cpp

// 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

#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();
}

实验结果：

 

问题1：t.h 中不能去掉line36

原因：友元函数要通过相应的类或对象名来访问，直接访问会使编译器找不到声明。

问题2：t.h中

line 9 ：普通构造函数，在对象被创建时利用特定的值构造对象，将对象初始化为一个特殊的状态。 调用时机：在对象被创建时自动调用。

line10：复制构造函数：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：当用类的一个对象去初始化该类的另一个对象时；如果函数的形参是类的对象，调用函数时，进行形参和实参结合时；如果函数的返回值是类的对象，函数执行完成返回调用者时。

line11：通过引用已有对象来安全地构造新对象。调用时机：当引用对象用于构造新对象时。

line12：析构函数：用来完成对象被删除前的清理工作，释放相应内存空间。调用时机：在对象的生存期即将结束的时候。

问题3：不能。

 

 

任务2：

Complex.h

#include <stdlib.h>
#include <string>
#include <cmath>

using namespace std;

class Complex {
public:
    Complex();
    Complex(double r, double i);
    Complex(double r);
    Complex(const Complex& c);
    static const string doc;
    double const get_real();
    double const get_imag();
    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(Complex c);
    friend double abs(Complex c);
private:
    double real;
    double imag;
};

 

 Complex.cpp

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

const string Complex::doc{ "a simplified Complex calss" };

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

Complex::Complex(double r) {
    real = r; 
    imag = 0;
}

Complex::Complex() { 
    real = 0;
    imag = 0;
}

Complex::Complex(const Complex& c) {
    real = c.real;
    imag = c.imag;
}

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

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

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

Complex add(const Complex& c1, const Complex& c2) {
    Complex s;
    s.real += c1.real + c2.real;
    s.imag += c1.imag + c2.imag;
    return s;
}

bool is_equal(const Complex& c1, const Complex& c2) {
    if (c1.real == c2.real && c1.imag == c2.imag)
        return true;
    else return false;
}

bool is_not_equal(const Complex& c1, const Complex& c2) {
    if (c1.real == c2.real && c1.imag == c2.imag)
      return false;
    else return true;
}

void output(Complex c) {
    cout << c.real;
    if (c.imag < 0)
        cout << " - " << -c.imag << 'i' << endl;
    else
        cout << " + " << c.imag << 'i' << endl;
}

double abs(Complex c) {

    return sqrt(c.real * c.real + c.imag * c.imag);
}

test.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();
}

 

 

标准模板库的complex类使用十分简洁，清晰，各种运算也十分方便

 

任务4

Fraction.h

#pragma once
#include<iostream>
#include<string>
using namespace std;
class Fraction {
public:
    Fraction();
    Fraction(int a);
    Fraction(int a, int b);
    Fraction(const Fraction& f);
    static const string doc;
private:
    int up, down;
public:
    int get_up()const;
    int get_down()const;
    Fraction negative();
    friend void output(Fraction f);
    friend Fraction add(Fraction f1, Fraction f2);
    friend Fraction sub(Fraction f1, Fraction f2);
    friend Fraction mul(Fraction f1, Fraction f2);
    friend Fraction div(Fraction f1, Fraction f2);
};

 

Fraction.cpp

#include"Fraction.h"
using namespace std;
const string Fraction::doc{ "Fraction类 v 0.01版. 目前仅支持分数对象的构造、输出、加 / 减 / 乘 / 除运算." };
int gcd(int x, int y) {
            if (x == 0 || y == 0) {
                   return x ? y == 0 : y;
        
    }
            if (x % y == 0)
                    return y;
            else
                     return gcd(y, x % y);
    
}
Fraction::Fraction() {
    up = 1;
    down = 1;
}
Fraction::Fraction(int a) {
    up = a;
    down = 1;
}
Fraction::Fraction(int a, int b) {
    up=a/gcd(a, b);
    down = b / gcd(a, b);
}
Fraction::Fraction(const Fraction& f) {
    up = f.up;
    down = f.down;
}
int Fraction::get_up()const {

    return up;

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

}
Fraction Fraction::negative() {
    Fraction f3;
    f3.up = -up;
    f3.down = down;
    return f3;
}
void output(Fraction f) {
    if (f.down == 0) cout << "分母不能为0" << endl;
    else if (f.up == 0) {
        cout << "0" << endl;
    }
    else if (f.down == 1)cout << f.up << endl;
    else if (f.down == -1) cout << -f.up << endl;
    else if (f.down<0) cout <<- f.up << "/" << -f.down << endl;

    else
        cout << f.up << "/" << f.down << endl;
}
Fraction add(Fraction f1, Fraction f2) {
    return Fraction(f1.up * f2.down + f2.up * f1.down, f1.down * f2.down);
}
Fraction sub(Fraction f1, Fraction  f2) {
    return Fraction(f1.up * f2.down-f2.up*f1.down, f1.down * f2.down);
}
Fraction mul(Fraction f1, Fraction f2) {
    return Fraction(f1.up * f2.up, f1.down * f2.down);
}
Fraction div(Fraction f1, Fraction f2) {
    return Fraction(f1.up * f2.down, f1.down * f2.up);
}

 

 test.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();
}

 

 

 

 

任务5：

account.h

#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;
};

account.cpp

#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;
}

5.11.cpp

 

#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;
}