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



class Wheel
{
public:
    string brand;
    int year;
    void wheelPrintInfo();
};
void Wheel::wheelPrintInfo()
{
    cout << "我的轮胎品牌是：" << brand << endl;
    cout << "我的轮胎日期是：" << year << endl;
}

//在C++中，一个类包含另一个类的对象称为组合（Composition）
class Car{ //汽车“类”
    
public:
    string color; //颜色
    string brand; //品牌
    string type; //车型
    int year; //年限
    Wheel wl;
    Wheel *pwl;
    
    //函数指针，指向车介绍函数
    //其实也是成员数据，指针变量，指向函数的变量，并非真正的成员函数
    //保存某个函数地址的变量
    void (*printCarInfo)(string color,string brand,string type, int year);
    void (*carRun)(string type); //函数指针，指向车运行的函数
    void (*carStop)(string type); //函数指针，执行车停止的函数
    
    void realPrintCarInfo();//声明成员函数
};

void Car::realPrintCarInfo(){
    string str = "车的品牌是：" + brand
            + ",型号是: " + type
            + ",颜色是：" + color
            + ",上市年限是:" + std::to_string(year);
    cout << str << endl;
}
void bwmThreePrintCarInfo(string color,string brand,string type, int year)
{
    string str = "车的品牌是：" + brand
            + ",型号是: " + type
            + ",颜色是：" + color
            + ",上市年限是:" + std::to_string(year);//通过std::tostring()函数，将整型数转化成字符串
    cout << str << endl;
}
void A6PrintCarInfo(string color,string brand,string type, int year)
{
    string str = "车的品牌是：" + brand
            + ",型号是: " + type
            + ",颜色是：" + color
            + ",上市年限是:" + std::to_string(year);
    cout << str << endl;
}
int main()
{
    system("chcp 65001 > nul");//强制控制台用UTF-8编码
    Car BWMthree;
    BWMthree.color = "白色";
    BWMthree.brand = "宝马";
    BWMthree.type = "3系";
    BWMthree.year = 2023;
    BWMthree.wl.year = 2023;
    BWMthree.wl.brand = "米其林";
    BWMthree.wl.wheelPrintInfo();
    BWMthree.printCarInfo = bwmThreePrintCarInfo;
    BWMthree.printCarInfo(BWMthree.color,BWMthree.brand,BWMthree.type,BWMthree.year);
    BWMthree.realPrintCarInfo();
    
    Car *AodiA6 = new Car();
    AodiA6->color = "黑色";
    AodiA6->brand = "奥迪";
    AodiA6->type = "A6";
    AodiA6->year = 2008;
    AodiA6->pwl = new Wheel();
    AodiA6->pwl->year = 2024;
    AodiA6->pwl->brand = "kk牌";
    AodiA6->pwl->wheelPrintInfo();
    AodiA6->printCarInfo = A6PrintCarInfo;
    AodiA6->printCarInfo(AodiA6->color,AodiA6->brand,AodiA6->type,AodiA6->year);
    AodiA6->realPrintCarInfo();
    return 0;
}

5. 权限修饰

5.1 基本介绍

int i = 17; int* p = &i; *p = 20;

int& r = i;
double& s = d;

#include <iostream>
using namespace std;
// 函数声明
void swap(int& x, int& y);
int main ()
{
    system("chcp 65001 > nul");//强制控制台用UTF-8编码
    // 局部变量声明
    int a = 100;
    int b = 200;
    cout << "交换前，a 的值：" << a << endl;//100
    cout << "交换前，b 的值：" << b << endl;//200
    /* 调用函数来交换值 */
    swap(a, b);
    cout << "交换后，a 的值：" << a << endl;//200
    cout << "交换后，b 的值：" << b << endl;//100
    return 0;
}
// 函数定义
void swap(int& x, int& y)
{
    int temp;
    temp = x; /* 保存地址 x 的值 */
    x = y; /* 把 y 赋值给 x */
    y = temp; /* 把 x 赋值给 y */
    return;
}

#include <iostream>

using namespace std;

double vals[] = {10.1, 12.6, 33.1, 24.1, 50.0};

double& setValue(int i){
    double& ref = vals[i];
    return ref;//返回一个指向ref返回值的隐式指针
}



int main()
{
    system("chcp 65001 > nul");//强制控制台用UTF-8编码
    cout << "改变前的值" << endl;
    for ( int i = 0; i < 5; i++ ){
        cout << vals[i] << endl;
    }
    setValue(2) = 37.5;
    setValue(4) = 101.5;

    cout << "改变后的值" << endl;
    for ( int i = 0; i < 5; i++ ){
        cout << vals[i] << endl;
    }

    return 0;
}