实验1 类和对象

实验任务1

task1.cpp源码

// 标准库string, vector, array基础用法
#include <iostream>
#include <string>
#include <vector>
#include <array>

// 函数模板
// 对满足特定条件的序列类型T对象，使用范围for输出
template<typename T>
void output1(const T &obj) {
    for (auto i : obj)
        std::cout << i << ", ";
    std::cout << "\b\b \n";
}

// 函数模板
// 对满足特定条件的序列类型T对象，使用迭代器输出
template<typename T>
void output2(const T &obj) {
    for (auto p = obj.begin(); p != obj.end(); ++p)
        std::cout << *p << ", ";
    std::cout << "\b\b \n";
}

// array模板类基础用法
void test_array() {
    using namespace std;
    array<int, 5> x1; // 创建一个array对象，包含5个int元素，未初始化
    cout << "x1.size() = " << x1.size() << endl; // 输出元素个数
    x1.fill(42); // 把x1的所有元素都用42填充
    x1.at(0) = 999; // 把下标为0的元素值修改为999
    x1[4] = -999; // 把下表为4的元素值修改为-999
    cout << "x1: ";
    output1(x1); // 调用模板函数output1输出x1
    cout << "x1: ";
    output2(x1); // 调用模板函数output1输出x1
    array<int, 5> x2{x1};
    cout << boolalpha << (x1 == x2) << endl;
    x2.fill(22);
    cout << "x2: ";
    output1(x2);
    swap(x1, x2); // 交换array对象x1, x2
    cout << "x1: ";
    output1(x1);
    cout << "x2: ";
    output1(x2);
}

// vector模板类基础用法
void test_vector() {
    using namespace std;
    vector<int> v1;
    cout << v1.size() << endl; // 输出目前元素个数
    cout << v1.max_size() << endl; // 输出元素个数之最大可能个数
    v1.push_back(55); // 在v1末尾插入元素
    cout << "v1: ";
    output1(v1);
    vector<int> v2 {1, 0, 5, 2};
    v2.pop_back(); // 从v2末尾弹出一个元素
    v2.erase(v2.begin()); // 删除v2.begin()位置的数据项
    v2.insert(v2.begin(), 999); // 在v1.begin()之前的位置插入
    v2.insert(v2.end(), -999); // 在v1.end()之前的位置插入
    cout << v2.size() << endl;
    cout << "v2: ";
    output2(v2);
    vector<int> v3(5, 42); //创建vector对象，包含5个元素，每个元素值都是42
    cout << "v3: ";
    output1(v3);
    vector<int> v4(v3.begin(), v3.end() - 2); // 创建vector对象，以v3对象的[v3.begin(), v3.end()-2)区间作为元素值
    cout << "v4: ";
    output1(v4);
}

// string类基础用法
void test_string() {
    using namespace std;
    string s1{"oop"};
    cout << s1.size() << endl;
    for (auto &i : s1)
        i -= 32;
    s1 += "2023";
    s1.append(", hello");
    cout << s1 << endl;
}

int main() {
    using namespace std;
    cout << "===========测试1: array模板类基础用法===========" << endl;
    test_array();
    cout << "\n===========测试2: vector模板类基础用法===========" << endl;
    test_vector();
    cout << "\n===========测试3: string类基础用法===========" << endl;
    test_string();
}

运行测试结果

 

 

实验任务2

task2.cpp源码

#include <iostream>
#include <complex>

// 测试标准库提供的复数类模板complex
void test_std_complex() {
    using namespace std;
    complex<double> c1{3, 4}, c2{4.5};
    const complex<double> c3{c2};
    cout << "c1 = " << c1 << endl;
    cout << "c2 = " << c2 << endl;
    cout << "c3 = " << c3 << endl;
    cout << "c3.real = " << c3.real() << ", " << "c3.imag = " << c3.imag()
         << endl;
    cout << "c1 + c2 = " << c1 + c2 << endl;
    cout << "c1 - c2 = " << c1 - c2 << endl;
    cout << "abs(c1) = " << abs(c1) << endl; // abs()是标准库数学函数，对复数取模
    cout << boolalpha; // 设置bool型值以true/false方式输出
    cout << "c1 == c2: " << (c1 == c2) << endl;
    cout << "c3 == c2: " << (c3 == c2) << endl;
    complex<double> c4 = 2;
    cout << "c4 = " << c4 << endl;
    c4 += c1;
    cout << "c4 = " << c4 << endl;
}

int main() {
    test_std_complex();
}

运行测试结果

 

实验任务3

task3.cpp源码

// 一个简单的类T：定义、使用
#include <iostream>
#include <string>
using namespace std;

// 类T的声明
class T {
    public:
        T(int x = 0, int y = 0); // 带有默认形值的构造函数
        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 set_m1(int x); // 设置T类对象的数据成员m1
        int get_m1() const; // 获取T类对象的数据成员m1
        int get_m2() const; // 获取T类对象的数据成员m2
        void display() const; // 显示T类对象的信息
        friend void func(); // 声明func()为T类友元函数
    private:
        int m1, m2;
    public:
        static void disply_count(); // 类方法，显示当前T类对象数目
    public:
        static const string doc; // 类属性，用于描述T类
        static const int max_count; // 类属性，用于描述T类对象的上限
    private:
        static int count; // 类属性，用于描述当前T类对象数目
};

// 类的static数据成员：类外初始化
const string T::doc{"a simple class"};
const int T::max_count = 99;
int T::count = 0;

// 类T的实现
T::T(int x, int y): m1{x}, m2{y} {
    ++count;
    cout << "constructor called.\n";
}
T::T(const T &t): m1{t.m1}, m2{t.m2} {
    ++count;
    cout << "copy constructor called.\n";
}
T::T(T &&t): m1{t.m1}, m2{t.m2} {
    ++count;
    cout << "move constructor called.\n";
}
T::~T() {
    --count;
    cout << "destructor called.\n";
}
void T::set_m1(int x) {
    m1 = x;
}
int T::get_m1() const {
    return m1;
}
int T::get_m2() const {
    return m2;
}
void T::display() const {
    cout << m1 << ", " << m2 << endl;
}

// 类方法
void T::disply_count() {
    cout << "T objects: " << count << endl;
}

// 友元函数func()：实现
void func() {
    T t1;
    t1.set_m1(55);
    t1.m2 = 77; // 虽然m2是私有成员，依然可以直接访问
    t1.display();
}

// 测试
void test() {
    cout << "T class info: " << T::doc << endl;
    cout << "T objects max_count: " << T::max_count << endl;
    T::disply_count();
    T t1;
    t1.display();
    t1.set_m1(42);
    T t2{t1};
    t2.display();
    T t3{std::move(t1)};
    t3.display();
    t1.display();
    T::disply_count();
}

// 主函数
int main() {
    cout << "============测试类T============" << endl;
    test();
    cout << endl;
    cout << "============测试友元函数func()============" << endl;
    func();
}

运行测试结果

 

实验任务4

task4.cpp源码

#include <iostream>
#include <string>
#include <iomanip>
using namespace std;

// 矩形类Rect的定义
class Rect {
    private:
        static int size;
    public:
        static const string doc;
        static int size_info() {
            return size;
        }
        friend void test();
    private:
        double length, width;
    public:
        Rect(double l = 2.0, double w = 1.0) : length{l}, width{w} {
            size++;
        }
        Rect(const Rect &obj) : length{obj.length}, width{obj.width} {
            size++;
        }
        ~Rect() {
            size--;
        }
        double len() const {
            return length;
        }
        double wide() const {
            return width;
        }
        double area() const {
            return length * width;
        }
        double circumference() const {
            return 2 * (length + width);
        }
        void resize(double times) {
            length *= times;
            width *= times;
        }
        void resize(double l_times, double w_times) {
            length *= l_times;
            width *= w_times;
        }
};
int Rect::size = 0;
const string Rect::doc{"a simple Rect class"};

// 普通函数：输出矩形信息
void output(const Rect &r) {
    cout << "矩形信息: " << endl;
    cout << fixed << setprecision(2); // 控制输出格式：以浮点数形式输出，小数部分保留两位
    cout << "长: \t" << r.len() << endl;
    cout << "宽: \t" << r.wide() << endl;
    cout << "面积: \t" << r.area() << endl;
    cout << "周长: \t" << r.circumference() << endl;
}

// 测试代码
void test() {
    cout << "矩形类信息: " << Rect::doc << endl;
    cout << "当前矩形对象数目: " << Rect::size_info() << endl;
    Rect r1;
    output(r1);
    Rect r2(4, 3);
    output(r2);
    Rect r3(r2);
    r3.resize(2);
    output(r3);
    r3.resize(5, 2);
    output(r3);
    cout << "当前矩形对象数目: " << Rect::size_info() << endl;
}

// 主函数
int main() {
    test();
    cout << "当前矩形对象数目: " << Rect::size_info() << endl;
}

运行测试结果

 

实验任务5

task5.cpp源码

#include <iostream>
#include <cmath>

// 复数类Complex：定义
class Complex {
    private:
        double real, imag;
    public:
        Complex(double r = 0, double i = 0) : real{r}, imag{i} {};
        Complex(const Complex &c) :real{c.real},imag{c.imag} {};
        double get_real() const {
            return real;
        }
        double get_imag() const {
            return imag;
        }
        void add(const Complex &c) {
            real += c.get_real();
            imag += c.get_imag();
        }
        void show() {
            std::cout << real;
            if (imag>0) std::cout << " + " << abs(imag) << 'i';
            if (imag<0) std::cout << " - " << fabs(imag) << 'i';
        }
        void show() const {
            std::cout << real;
            if (imag>0) std::cout << " + " << abs(imag) << 'i';
            if (imag<0) std::cout << " - " << fabs(imag) << 'i';
        }
    public:
        friend Complex add(const Complex&, const Complex&);
        friend bool is_equal(const Complex&, const Complex&);
        friend double abs(const Complex&);
};
Complex add(const Complex &c1, const Complex &c2) {
    double r, i;
    r = c1.get_real() + c2.get_real();
    i = c1.get_imag() + c2.get_imag();
    Complex c(r, i);
    return c;
}
bool is_equal(const Complex &c1, const Complex &c2) {
    bool r, i;
    r = c1.get_real() == c2.get_real();
    i = c1.get_imag() == c2.get_imag();
    return r && i;
}
double abs(const Complex &c) {
    return sqrt(pow(c.get_real(), 2) + pow(c.get_imag(), 2));
}

// 复数类Complex: 测试
void test() {
    using namespace std;
    Complex c1(3, -4);
    const Complex c2(4.5);
    Complex c3(c1);
    cout << "c1 = ";
    c1.show();
    cout << endl;
    cout << "c2 = ";
    c2.show();
    cout << endl;
    cout << "c2.imag = " << c2.get_imag() << endl;
    cout << "c3 = ";
    c3.show();
    cout << endl;
    cout << "abs(c1) = ";
    cout << abs(c1) << endl;
    cout << boolalpha;
    cout << "c1 == c3 : " << is_equal(c1, c3) << endl;
    cout << "c1 == c2 : " << is_equal(c1, c2) << endl;
    Complex c4;
    c4 = add(c1, c2);
    cout << "c4 = c1 + c2 = ";
    c4.show();
    cout << endl;
    c1.add(c2);
    cout << "c1 += c2, " << "c1 = ";
    c1.show();
    cout << endl;
}

int main() {
    test();
}

运行测试结果