实验2 类和对象_基础编程1

实验任务1

代码：

t.h:

#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:

#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;
}

task.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;

    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();
}

运行截图：

问题1：

 不能去掉，因为func在类内声明了友元函数，但没有声明为普通函数，删掉会显示找不到此函数。

问题2：line9是普通构造函数，给定了两个默认的参数初始值。在系统定义类的对象时，如果定义形式是T t(括号内可以有0到两个参数)，就调用该函数。

line10是复制构造函数，将t指向调用时输入的对象，但不改变其的值。

line11是移动构造函数，通过移动而不复制实参的方式提高运行效率。

line12是析构函数，之前的各类构造函数调用完成后，调用该函数，释放他们的空间。一般在主函数结束后调用。

问题3：不能

实验任务2

代码：

complex.h:

#pragma once
#include<string>
class Complex {
public:
    static std::string doc;
    Complex(double x1 = 0, double  y1 = 0);
    Complex(const Complex& c);
    ~Complex() {}
    double get_real() ;
    double get_imag() ;
    void add(const Complex &d) ;
    friend Complex add(const Complex &e, const Complex &f);
    friend bool is_equal(const Complex &e,const Complex &f);
    friend bool is_not_equal(const Complex &e,const Complex &f);
    friend void output(const Complex& e);
    friend double abs(const Complex &g);

private:
    double x, y;
};

bool is_equal(const Complex &e,const Complex&f);
bool is_not_equal(const Complex &e,const Complex&f);
void output(const Complex& e);

complex.cpp:

#include"complex.h"
#include<iostream>
#include<string>
Complex::Complex(double x1, double y1):x{ x1 }, y{ y1 } {}

Complex::Complex(const Complex& c) :x{ c.x }, y{ c.y } {}
double Complex::get_real() {
    return x;
}
double Complex::get_imag() {
    return y;
}
void Complex::add(const Complex& d) {
    x += d.x;
    y += d.y;
}
Complex add(const Complex& e,const Complex& f) {
    Complex h;
    h.x = e.x + f.x;
    h.y = e.y + f.y;
    return h;
}
bool is_equal(const Complex &e,const Complex &f) {
    return e.x == f.x && e.y == f.y;
}
bool is_not_equal(const Complex& e, const Complex& f) {
    return e.x != f.x || e.y != f.y;
}

void output(const Complex& e) {
    std::cout << e.x << e.y << "i";
}
double abs(const Complex& g) {
    return sqrt(g.x * g.x + g.y * g.y);
}
 std::string Complex::doc = "a simplified complex class";

task2.cpp:

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

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();
}

运行截图：

实验任务3

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();
}

运行截图：

实验任务4

代码：

Fraction.h:

#pragma once
#include<string>

class Fraction {
public:
    static const std::string doc;
    Fraction(int x=1, int y = 1);
    Fraction(const Fraction& p);
    int get_up();
    int get_down();
    Fraction negative();

public:
    friend void output(Fraction p);
    friend Fraction add(const Fraction& a, const Fraction& b);
    friend Fraction sub(const Fraction& a, const Fraction& b);
    friend Fraction mul(const Fraction& a, const Fraction& b);
    friend Fraction div(const Fraction& a, const Fraction& b);

private:
    int up, down;

};

void output( Fraction p);


int computeGCD(int a, int b);

Fraction.cpp:

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

const std::string Fraction::doc = "Fraction类v0.01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 x,int y):up{x},down{y}{}
Fraction::Fraction(const Fraction &p):up{p.up},down{p.down}{}
int Fraction::get_up(){
    int gcd = computeGCD(up, down);
    up /= gcd;
    down /= gcd;
    return up;
}
 int Fraction::get_down(){
     int gcd = computeGCD(up,down);
     up /= gcd;
     down /= gcd;
     return down;
}
Fraction Fraction::negative() {
    return Fraction(-up, down);
}
void output(Fraction p) {
    int gcd = computeGCD(p.up, p.down);
    p.up /= gcd;
    p.down /= gcd;
    if (p.down == 1) {
        std::cout << p.up;
    }
    else if ( p.down > 0&&p.down!=1) {
        std::cout << p.up << "/" << p.down;
    }
    else if (p.down == 0) {
        std::cout << "分母不能为0";
    }
    else std::cout << -p.up << "/" << -p.down;
}
Fraction add(const Fraction& a, const Fraction& b) {
    Fraction c;
    c.up = a.up*b.down+ b.up*a.down;
    c.down = a.down * b.down;
    return c;
}
Fraction sub(const Fraction& a, const Fraction& b) {
    Fraction c;
    c.down = a.down * b.down;
    c.up = a.up * b.down - a.down * b.up;
    int gcd = computeGCD(c.up, c.down);
    c.up /= gcd;
    c.down /= gcd;
    return c;
}
Fraction mul(const Fraction& a, const Fraction& b) {
    Fraction c;
    c.down = a.down * b.down;
    c.up = a.up * b.up;
    int gcd = computeGCD(c.up, c.down);
    c.up /= gcd;
    c.down /= gcd;
    return c;
}
Fraction div(const Fraction& a, const Fraction& b) {
    Fraction c;
    if (b.up != 0 && b.down != 0) {
        c.down = a.down * b.up;
        c.up = a.up * b.down;
        int gcd = computeGCD(c.up, c.down);
        c.up /= gcd;
        c.down /= gcd;
        return c;
    }
    else {
        return Fraction(1, 0);
    }
}

int computeGCD(int a, int b) {
    while (b != 0) {
        int temp = b;
        b = a % b;
        a = temp;
    }
    return a < 0 ? -a : a; 
}

task4.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();
}

运行截图：

实验任务5

代码：

account.h:

#pragma once
#ifndef  ACCOUNT_H
#define  ACCOUNT_H
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 getBanlance()const { return balance; }
    double getRate()const { return rate; }
    static double getTotal() { return total; }
    void deposit(int date, double amcount);
    void withdraw(int date, double amount);
    void settle(int date);
    void show()const;
};
#endif

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 > getBanlance())
        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, 0.0015);
    SavingsAccount sa1(1, 58320212, 0.0015);
    
    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;
}

运行截图：

实验总结：在类的定义中有许多小细节，要十分注意，不然报错一大堆就会很头疼。