实验二 类和对象_基础编程1
实验任务一：
#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();
// 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; }
#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(); }
问题一：
不能，编译器找不到标识符，因为友元函数只声明在类中，声明被封装到类中，对外不可见，如果不在外声明则找不到
问题二：
普通构造函数：用来创建对象； 在创建对象时调用
复制构造函数：用来给对象赋值 ； 1、用一个对象初始化另一个对象时调用 2、在调用函数使用值传递时，将实参赋值给形参 3、在返回对象的函数调用中，返回一个对象时创建的临时对象时调用
移动构造函数：避免拷贝对象，而是改变资源指向，提高效率 ； 在显示调用移动构造函数时调用
析构函数：用来对象被删除前的清理工作，调用后，对象将不存在； 在对象生存期快要结束时调用
问题三：不可以
实验任务二：
#pragma once #include<string> using namespace std; class Complex { private: double real; double imag; public: static string doc; Complex(double x = 0, double y = 0); Complex(const Complex& c); double get_real() const; double get_imag() const ; 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(const Complex &c); friend double abs(const Complex &c); }; //普通函数声明 Complex add(const Complex& c1, const Complex& c2); bool is_equal(const Complex& c1, const Complex& c2); bool is_not_equal(const Complex& c1, const Complex& c2); void output(const Complex& c); double abs(const Complex& c);
#include "C:/Users/29114/source/repos/MAJORCPP/Complex.h" #include<iostream> #include<math.h> using namespace std; string Complex ::doc = "a simplified complex class"; Complex ::Complex(double x, double y ):real(x),imag(y){} Complex::Complex(const Complex& c) { real = c.real; imag = c.imag; } double Complex::get_real() const { return real; } double Complex::get_imag() const { return imag; } void Complex::add(const Complex& c) { real = c.real + real; imag += c.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 &&c2.imag == c1.imag) return true; else return false; } bool is_not_equal(const Complex& c1, const Complex& c2) { if (is_equal(c1,c2)) return false; else return true; } void output(const Complex& c) { if(c.imag>=0) cout << c.real << " + " << c.imag << "i"; else cout << c.real << c.imag << "i"; } double abs(const Complex& c) { return sqrt(c.real * c.real + c.imag * c.imag); }
#include <iostream> #include "C:/Users/29114/source/repos/MAJORCPP/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(); }
实验任务三：
#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(); }
使用了相应的构造函数，使用了加、取模等操作
实验任务4：
#pragma once #include<iostream> using namespace std; class Fraction { public: const static string doc; private: int up; int down; public: //先声明，在.cpp中实现 Fraction(int n); Fraction(int a, int b); Fraction(const Fraction& p); int get_up(); int get_down(); Fraction negative();//返回求负对象 friend void output(Fraction a); friend Fraction add(Fraction a, Fraction b); friend Fraction sub(Fraction a, Fraction b); friend Fraction mul(Fraction a, Fraction b); friend Fraction div(Fraction a, Fraction b); }; //普通函数声明 void output(Fraction a); Fraction add(Fraction a, Fraction b); Fraction sub(Fraction a, Fraction b); Fraction mul(Fraction a, Fraction b); Fraction div(Fraction a, Fraction b); int gcd(int a, int b);
#include"Fraction.h" #include<iostream> #include<cstdlib> using namespace std; /* Fraction(int n):up=n,down=1{} Fraction(int a,int b):up=a,down=b{} Fraction(const Fraction &p); int get_up(Fraction a); int get_down(Fraction a); Fraction negative();//返回求负对象 friend void output(Fraction a); friend Fraction add(Fraction a,Fraction b); friend Fraction sub(Fraction a,Fraction b); friend Fraction mul(Fraction a,Fraction b); friend Fraction div(Fraction a,Fraction b); */ 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."; Fraction::Fraction(int n) :up(n), down(1){} 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() { return up/ gcd(up, down); } int Fraction::get_down() { return down / gcd(up, down); } Fraction Fraction::negative() { Fraction a(-1*up,down); return a; } void output(Fraction a) { int b = gcd(a.up, a.down); if ((a.up < 0 && a.down>0) || (a.up > 0 && a.down < 0)) cout << "-" << abs(a.up / b) << "/" << abs(a.down / b); else if (a.down == 1) cout << a.up; else if (a.down == 0) cout << "分子不能为0"; else if (a.up == 0) cout << "0"; else cout << a.up / b << "/" << a.down / b; } Fraction add(Fraction a, Fraction b) { int down1 = abs(a.down * b.down) / gcd(a.down, b.down); int up1 = down1 / a.down * a.up+ down1 / b.down * b.up; Fraction c(up1, down1); return c; } Fraction sub(Fraction a, Fraction b) { int down = abs(a.down * b.down) / gcd(a.down, b.down); int up1 = down / a.down * a.up; int up2 = down / b.down * b.up; Fraction c(up1 - up2, down); return c; } Fraction mul(Fraction a, Fraction b) { Fraction c(a.up * b.up, a.down * b.down); return c; } Fraction div(Fraction a, Fraction b) { Fraction c(a.up * b.down, a.down * b.up); return c; } int gcd(int a, int b) { while (b != 0) { int temp = b; b = a % b; a = temp; } return a; }
#include <iostream> #include "C:/Users/29114/source/repos/MAJORCPP/Fraction.h" 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
#ifndef ACCOUNT_H #define ACCOUNT_H #include<iostream> class SavingAccount{ 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: SavingAccount(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);//存入现金 void withdraw(int date,double amount);//取出现金 //结算利息，每年1月1日调用一次下函数 void settle(int date); void show()const; }; #endif
#include"account.h" #include<iostream> #include<cmath> using namespace std; double SavingAccount::total=0; SavingAccount::SavingAccount(int date,int id,double rate):id{id},balance(0),rate(rate),lastDate(date),accumulation(0){ cout<<date<<"\t#"<<id<<"is created"<<endl; } void SavingAccount::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 SavingAccount::deposit(int date,double amount) { record(date,amount); } void SavingAccount::withdraw(int date,double amount) { if(amount>getBalance()) cout<<"Error:not enough money"<<endl; else record(date,-amount); } void SavingAccount::settle(int date) { double interest=accumulate(date)*rate/365; if(interest!=0) record(date,interest); accumulation=0; } void SavingAccount::show()const { cout<<"#"<<id<<"\tBalance:"<<balance; }
#include"account.h" #include<iostream> 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.withdraw(60,4000); sa0.settle(90); sa1.settle(90); sa0.show();cout<<endl; sa1.show();cout<<endl; cout<<"Total:"<<SavingAccount::getTotal()<<endl; return 0; }
