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  • c++面向对象之封装

    c++面向对象三大特性:封装、继承、多态;

    封装的意义:

    • 将属性和行为作为一个整体,表现生活中的事物;
    • 将属性和行为加以权限控制;
    #include<iostream>
    using namespace std;
    
    class Student {
    public:
        string name;
        int age;
        double score;
        void show() {
            cout << "姓名:" << name << endl;
            cout << "年龄:" << age << endl;
            cout << "分数:" << score << endl;
        }
        void setName(string name) {
            this->name = name;
        }
        void setAge(int age) {
            this->age = age;
        }
        void setScore(double score) {
            this->score = score;
        }
        string getName() {
            return this->name;
        }
        int getAge() {
            return this->age;
        }
        double getScore() {
            return this -> score;
        }
    };
    
    int main() {
        Student s1;
        s1.name = "tom";
        s1.age = 12;
        s1.score = 99.0;
        s1.show();
        s1.setName("jack");
        s1.setAge(22);
        s1.setScore(100.0);
        cout << s1.getName() << endl;
        cout << s1.getAge() << endl;
        cout << s1.getScore() << endl;
        s1.show();
        system("pause");
        return 0;
    }

    输出:

    c++中的访问权限:

    • public:类内可以访问,类外可以访问;
    • private:类内可以访问,类外不可以访问;子类可以访问父类的保护内容;
    • protected:类内可以访问,类外不可以访问;子类不可以访问父类的保护内容;
    #include<iostream>
    using namespace std;
    
    class Student {
    private:
        string name;
        int age;
        double score;
    public:
        void setName(string name) {
            this->name = name;
        }
        void setAge(int age) {
            this->age = age;
        }
        void setScore(double score) {
            this->score = score;
        }
        string getName() {
            return this->name;
        }
        int getAge() {
            return this->age;
        }
        double getScore() {
            return this -> score;
        }
        void show() {
            cout << "姓名:" << name << endl;
            cout << "年龄:" << age << endl;
            cout << "分数:" << score << endl;
        }
    };
    
    int main() {
        Student s1;
        /* 此时这样访问会报错
        s1.name = "tom";
        s1.age = 12;
        s1.score = 99.0;
        */
        s1.show();
        //可以通过set和get方法去操作成员私有变量
        s1.setName("jack");
        s1.setAge(22);
        s1.setScore(100.0);
        cout << s1.getName() << endl;
        cout << s1.getAge() << endl;
        cout << s1.getScore() << endl;
        s1.show();
        system("pause");
        return 0;
    }

    输出:

    对于全局变量,如若不初始化,都会默认有一个固定的值;对于局部变量,如若不初始化,默认会有一个随机值。

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  • 原文地址:https://www.cnblogs.com/xiximayou/p/12092373.html
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