1.封装

//C++三大特性：封装、继承和多态
//封装的意义：将属性(成员变量)和行为（成员函数或者方法）作为一个整体，表现生活中的事物，将属性和行为加以权限控制

//设计一个圆类，求圆的周长

#include<iostream>
using namespace std;

#define PI 3.14
class Circle
{
    //访问权限
public://公共权限
    int m_R;

    //行为
    //获取圆的周长
    double calculateZC()
    {
        return 2 * PI * m_R;
    }

};
class Student 
{
public:
    string m_Name;
    int m_ID;

    void setName(string name)
    {
        m_Name = name;
    }
    void setID(int id)
    {
        m_ID = id;
    }
    void showStudent()
    {
        cout << "姓名：" << m_Name << endl << "学号:" << m_ID << endl;
    }
};
int main()
{
    Circle c1;
    c1.m_R = 10;
    cout << "圆的周长：" << c1.calculateZC() << endl;

    Student s1;
    s1.m_Name = "仙思凡";
    s1.m_ID = 1001;
    s1.showStudent();

    Student s2;
    s2.setID(2001);
    s2.setName("aha");
    s2.showStudent();
    system("pause");
    return 0;
}