C++面向?qū)ο笕筇匦裕?code>封裝、繼承、多態(tài)
1.封裝
1.1封裝的意義
- 將屬性和行為作為一個整體
- 將屬性和行為加以權(quán)限控制
封裝意義一：
語法：class 類名{ 訪問權(quán)限： 屬性 / 行為 };
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//實(shí)例1#define _CRT_SECURE_NO_WARNINGS 1//求圓的周長#include<iostream>using namespace std;#define pi 3.14class circle{public: int m_d;//直徑 double calculate() { return pi*m_d; }};int main(){ circle c1; c1.m_d = 10; cout << "圓周長為" << c1.calculate() << endl; system("pause"); return 0;} |
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//實(shí)例2#define _CRT_SECURE_NO_WARNINGS 1#include<iostream>using namespace std;#include <string>class Student{public: string m_name; int m_num; void showStudent() { cout << " 姓名：" << "\t" << m_name << " 學(xué)號：" << m_num << endl; } void setname(string name) { m_name = name; } void setnum(int num) { m_num = num; }};int main(){ Student s1; s1.setname("zhangsan"); s1.setnum(2001); s1.showStudent(); Student s2; s2.setname("lisi"); s2.setnum(2002); s2.showStudent(); system("pause"); return 0;} |
總結(jié)：類中的 屬性 和 行為 統(tǒng)一稱為 成員
類中的 屬性 又稱為 成員屬性 成員變量
類中的 行為 又稱為 成員函數(shù) 成員方法
封裝意義二
訪問權(quán)限有三種
公共權(quán)限： public 成員類內(nèi)可以訪問，類外可以訪問
保護(hù)權(quán)限： protected 成員類內(nèi)可以訪問，類外不可以訪問 兒子可以訪問父親中的保護(hù)內(nèi)容
私有權(quán)限： private 成員類內(nèi)可以訪問，類外不可以訪問 兒子不可以訪問父親中的保護(hù)內(nèi)容
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#define _CRT_SECURE_NO_WARNINGS 1#include<iostream>using namespace std;#include <string>class Student{public: string m_name;protected: int m_num;private: int m_age;public: void func() { m_name = "lili"; m_num = 1; m_age = 30; }private: void func1() { m_name = "lili"; m_num = 1; m_age = 30; }};int main(){ Student s1; s1.m_name = "lilllll"; //s1.m_num = 2;//不可訪問 //s1.m_age = 20;//不可訪問 s1.func(); //s1.func1();//不可訪問 system("pause"); return 0;} |
1.2 struct 和 class 區(qū)別
在C++中 struct 和 class 區(qū)別在于 默認(rèn)的訪問權(quán)限不同
- struct 默認(rèn)權(quán)限為公共
- class 默認(rèn)權(quán)限為私有
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#define _CRT_SECURE_NO_WARNINGS 1#include<iostream>using namespace std;class C1{ string m_a;};struct C2{ string m_b;};int main(){ //C1 c1; //c1.m_a = "lili";//不可訪問 C2 c2; c2.m_b = "lili"; system("pause"); return 0;} |
1.3 成員屬性設(shè)置為私有
優(yōu)點(diǎn)：
- 將所有成員屬性設(shè)置為私有，可以自己控制讀寫權(quán)限
- 對于寫權(quán)限，我們可以檢測數(shù)據(jù)的有效性
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#define _CRT_SECURE_NO_WARNINGS 1#include<iostream>#include <string>using namespace std;class C1{public: void setname(string name) { m_name = name; } string getname() { return m_name; } int getnum() { return m_num; } void setage(int age) { m_age = age; }private: string m_name; int m_num; int m_age;};int main(){ C1 c; c.setname("yangyang");//可寫 cout << c.getname() << endl;//可讀 cout << c.getnum() << endl;//只讀 c.setage(30);//只寫 system("pause"); return 0;} |
好的，到這里封裝就算是學(xué)到手了，可以進(jìn)行兩個小案例：
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#define _CRT_SECURE_NO_WARNINGS 1#include<iostream>#include <string>using namespace std;class Cube{public: void setchang(int chang) { m_c = chang; } void setkuan(int kuan) { m_k = kuan; } void setgao(int gao) { m_g = gao; } int getchang() { return m_c; } int getkuan() { return m_k; } int getgao() { return m_g; } int S() { return 2 * (m_c*m_g + m_c*m_k + m_g*m_k); } int V() { return m_c*m_g*m_k; } bool isSamebyclass(Cube &c) { if (m_c == c.getchang() && m_g == c.getgao() && m_k == c.getkuan()) { return true; } return false; }private: int m_c; int m_k; int m_g;};bool isSame1(Cube &c1, Cube &c2){ if (c1.getchang() == c2.getchang() && c1.getgao() == c2.getgao() && c1.getkuan() == c2.getkuan()) { return true; } return false;}int main(){ Cube c1; c1.setchang(10); c1.setkuan(10); c1.setgao(10); cout << "面積：" << c1.S() << endl; cout << "體積：" << c1.V() << endl; Cube c2; c2.setchang(11); c2.setkuan(11); c2.setgao(11); cout << "面積：" << c2.S() << endl; cout << "體積：" << c2.V() << endl; bool ret = isSame1(c1, c2); if (ret) { cout << "全局函數(shù)判斷：兩個立方體相等" << endl; } else { cout << "全局函數(shù)判斷：兩個立方體不相等" << endl; } ret = c1.isSamebyclass(c2); if (ret) { cout << "成員函數(shù)判斷：兩個立方體相等" << endl; } else { cout << "成員函數(shù)判斷：兩個立方體不相等" << endl; } system("pause"); return 0;} |
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#define _CRT_SECURE_NO_WARNINGS 1#include<iostream>#include <string>using namespace std;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;};void C_and_P(Circle &c, Point &p){ int distance = (c.getcenter().getX() - p.getX())*(c.getcenter().getX() - p.getX()) + (c.getcenter().getY() - p.getY())* (c.getcenter().getY() - p.getY()); int doubleR = c.getR()*c.getR(); if (distance==doubleR) { cout << "點(diǎn)在圓上" << endl; } else if (distance<doubleR) { cout << "點(diǎn)在圓內(nèi)" << endl; } else { cout << "點(diǎn)在圓外" << endl; }}int main(){ Point p; p.setX(10); p.setY(30); Circle c; c.setR(10); Point center; center.setX(26); center.setY(43); C_and_P(c, p); system("pause"); return 0;} |
總結(jié)
本篇文章就到這里了，希望能夠給你帶來幫助，也希望您能夠多多關(guān)注服務(wù)器之家的更多內(nèi)容！
原文鏈接：https://blog.csdn.net/GiGi_Princess/article/details/120057308
