封装(个人学习笔记黑马学习)

1、格式

#include <iostream>
using namespace std;const double PI =3.14;//设计一个圆类，求圆的周长
class Circle {//访问权限//公共权限
public://属性//半径int m_r;//行为//获取圆的周长double calculateZC() {return 2 * PI * m_r;}
};int main() {//通过圆类创造具体的圆Circle c1;c1.m_r = 10;cout << "圆的周长：" << c1.calculateZC() << endl;system("pause");return 0;
}

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2、案例：设计学生类

设计一个学生类，属性有姓备和学号，可以给姓名和学号赋值，可以显示学生的姓名和学号

#include <iostream>
using namespace std;
#include <string>class Studentt {
public:string m_Name;int m_Id;void showStudent() {cout << "姓名：" << m_Name << " 学号：" << m_Id << endl;}//给姓名赋值void setName(string name) {m_Name = name;}//给学号赋值void setId(int id) {m_Id = id;}
};int main() {Studentt s1;//s1.m_Name = "张三";s1.setName("张三");s1.setId(1);s1.showStudent();Studentt s2;s2.m_Name = "李四";s2.m_Id = 2;s2.showStudent();system("pause");return 0;
}

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3、权限访问

1. public公共权限

2. protected 保护权限

3. private私有权限

#include <iostream>
using namespace std;
#include <string>//1. public公共权限     成员 类内可以访问 类外也可以访问
//2. protected保护权限  成员 类内可以访问 类外不可以访问   儿子可以访问父亲中的保护内容
//3. private私有权限    成员 类内可以访问 类外不可以访问   儿子不可以访问父亲中保护的内容class Person {//公共权限
public:string m_Name;//保护权限
protected:string m_Car;//私有权限
private:int m_Password;public:void func() {m_Name = "张三";m_Car = "拖拉机";m_Password = 123456;}};int main() {Person p1;p1.m_Name = "李四";//p1.m_Car = "奔驰";//保护权限内容 在类外访问不到//p1.m_Password = 23456;//私有权限内容，在类外访问不到system("pause");return 0;
}

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4、class和struct区别

• struct 默认权限为公共
• class默认权限为私有

#include <iostream>
using namespace std;
#include <string>class C1 {int m_A;//默认权限是私有
};struct C2 {int m_A;//默认权限是公共
};int main() {C1 c1;//c1.m_A = 100;C2 c2;c2.m_A = 100;system("pause");return 0;
}

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5、成员属性私有化

#include <iostream>
using namespace std;
#include <string>class Person {public://设置姓名void setName(string name) {m_Name = name;}//获取姓名string getName() {return m_Name;}int getAge() {m_Age = 10;return m_Age;}void setLover(string lover) {m_Lover = lover;}private:string m_Name;//可读可写int m_Age;//只读string m_Lover;//只写
};int main() {Person p;p.setName("张三");cout << "姓名："<<p.getName()<< endl;cout << "年龄：" << p.getAge() << endl;p.setName("梨花");system("pause");return 0;
}

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6、案例设计：立方体类

设计立方体类(Cube)
求出立方体的面积和体积
分别用全局函数和成员函数判断两个立方体是否相等

#include <iostream>
using namespace std;
#include <string>class Cube {public:void setL(int l) {m_L = l;}int getL() {return m_L;}void setW(int w) {m_W = w;}int getW() {return m_W;}void setH(int h) {m_H = h;}int getH() {return m_H;}int calculateS() {return 2 * m_L * m_W + 2 * m_W * m_H + 2 * m_L * m_H;}int calculateV() {return m_H * m_L * m_W;}//利用成员函数判断两个立方体是否相等bool isSameByClass(Cube& c) {if (m_L == c.getL() && m_W == c.getW() && m_H == c.getH()) {return true;}return false;
}private:int m_L;int m_W;int m_H;
};//利用全局函数判断 两个立方体是否相等
bool isSame(Cube& c1, Cube& c2) {if (c1.getL() == c2.getL() && c1.getW() == c2.getW() && c1.getH() == c2.getH()) {return true;}return false;}int main() {Cube c1;c1.setL(10);c1.setW(10);c1.setH(10);cout << "c1的面积为：" << c1.calculateS() << endl;cout << "c1的体积为：" << c1.calculateV() << endl;Cube c2;c2.setL(10);c2.setW(10);c2.setH(10);cout << "c2的面积为：" << c2.calculateS() << endl;cout << "c2的体积为：" << c2.calculateV() << endl;bool ret=isSame(c1, c2);if (ret) {cout << "c1,c2相等" << endl;}else {cout << "c1,c2不相等" << endl;}int ret2= c1.isSameByClass(c2);if (ret2) {cout << "c1,c2相等" << endl;}else {cout << "c1,c2不相等" << endl;}int ret3 = c2.isSameByClass(c1);if (ret3) {cout << "c1,c2相等" << endl;}else {cout << "c1,c2不相等" << endl;}system("pause");return 0;
}

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7、案例设计：点和圆的关系

设计一个圆形类(Circle)，和一个点类 (Point) ，计算点和圆的关系

#include <iostream>
using namespace std;
#include <string>class Point {
public:void setX(int x) {m_X = x;}int getX() {return m_X;}void setY(int y) {m_Y = y;}int getY() {return m_Y;}private:int m_X;int m_Y;
};class Circle {public:void setR(int r) {m_R = r;}int getR() {return m_R;}void setCenter(Point center) {m_Center = center;}Point getCenter() {return m_Center;}private:int m_R;Point m_Center;//圆心
};void isInCircle(Circle& c, Point& p) {//计算两点之间距离 平方int distance =(c.getCenter().getX() - p.getX()) * (c.getCenter().getX() - p.getX()) +(c.getCenter().getY() - p.getY()) * (c.getCenter().getY() - p.getY());//计算半径的平方int rDistance = c.getR() * c.getR();//判断关系if (distance == rDistance) {cout << "点在圆上" << endl;}else if (distance > rDistance) {cout << "点在圆外" << endl;}else {cout << "点在圆内" << endl;}
}int main(){//创建圆Circle c;c.setR(10);Point center;center.setX(10);center.setY(10);c.setCenter(center);//创建点Point p;p.setX(10);p.setY(11);//判断关系isInCircle(c, p);system("pause");return 0;
}

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point.h

#pragma once//防止头文件重复包含
#include <iostream>
using namespace std;class Point {
public:void setX(int x);int getX();void setY(int y);int getY();
private:int m_X;int m_Y;
};

point.cpp

#include "point.h"void Point:: setX(int x) {m_X = x;
}
int Point:: getX() {return m_X;
}void Point:: setY(int y) {m_Y = y;
}
int Point:: getY() {return m_Y;
}

circle.h

#pragma once
#include <iostream>
using namespace std;
#include "point.h"class Circle {public:void setR(int r);int getR();void setCenter(Point center);Point getCenter();private:int m_R;Point m_Center;//圆心
};

circle.cpp

#include "circle.h"void Circle:: setR(int r) {m_R = r;}int Circle:: getR() {return m_R;}void Circle:: setCenter(Point center) {m_Center = center;}Point Circle:: getCenter() {return m_Center;}

面向对象.cpp

#include <iostream>
using namespace std;
#include <string>
#include "point.h"
#include "circle.h"//class Point {
//public:
//	void setX(int x) {
//		m_X = x;
//	}
//	int getX() {
//		return m_X;
//	}
//
//	void setY(int y) {
//		m_Y = y;
//	}
//	int getY() {
//		return m_Y;
//	}
//
//private:
//	int m_X;
//	int m_Y;
//};//class Circle {
//
//public:
//	void setR(int r) {
//		m_R = r;
//	}
//	int getR() {
//		return m_R;
//	}
//
//	void setCenter(Point center) {
//		m_Center = center;
//	}
//	Point getCenter() {
//		return m_Center;
//	}
//
//private:
//	int m_R;
//
//	Point m_Center;//圆心
//};void isInCircle(Circle& c, Point& p) {//计算两点之间距离 平方int distance =(c.getCenter().getX() - p.getX()) * (c.getCenter().getX() - p.getX()) +(c.getCenter().getY() - p.getY()) * (c.getCenter().getY() - p.getY());//计算半径的平方int rDistance = c.getR() * c.getR();//判断关系if (distance == rDistance) {cout << "点在圆上" << endl;}else if (distance > rDistance) {cout << "点在圆外" << endl;}else {cout << "点在圆内" << endl;}
}int main(){//创建圆Circle c;c.setR(10);Point center;center.setX(10);center.setY(0);c.setCenter(center);//创建点Point p;p.setX(10);p.setY(10);//判断关系isInCircle(c, p);system("pause");return 0;
}