How to implement object-oriented programming principles in C++ class design?

Object-oriented programming principles in C++: Encapsulation: Encapsulate data and methods in an entity called a class to protect data and promote code reuse. Inheritance: allows derived classes to inherit data and methods from base classes, promoting code reuse and expressing parent-child relationships. Polymorphism: allows objects in different classes to exhibit different behaviors according to the class they belong to, realizing common code logic.

Object-Oriented Programming Principles in C++ Class Design

Object-oriented programming (OOP) is a set of guiding principles for Organize and design computer programs. The C++ language supports OOP well through the concept of classes. Understanding OOP principles is critical to designing efficient, maintainable, and reusable C++ code.

Three major OOP principles

• Encapsulation: Encapsulation bundles data and methods together as a unit and only allows Access internal details through a public interface. This helps protect data from accidental changes and promotes code reuse.
• Inheritance: Inheritance allows one class to inherit data and methods from another class (called a base class). This allows parent-child relationships to be expressed in code and promotes code reuse.
• Polymorphism: Polymorphism allows objects to exhibit different behaviors depending on the class they belong to. This allows you to write generic code that can handle many types of objects.

Implementation in C++

Encapsulation:

class Person {
private:
    int age;
    string name;

public:
    void setAge(int age) { this->age = age; }
    void setName(string name) { this->name = name; }

    int getAge() const { return age; }
    string getName() const { return name; }
};

In the above example, Person The class encapsulates the age and name data and provides public functions to access and modify these data.

Inheritance:

class Employee : public Person {
private:
    int salary;

public:
    void setSalary(int salary) { this->salary = salary; }

    int getSalary() const { return salary; }
};

Employee class inherits age and ## from the Person class #name data, and salary data added. This establishes a parent-child relationship between Employee and Person.

Polymorphism:

class Shape {
public:
    virtual void draw() = 0; // 纯虚函数
};

class Rectangle : public Shape {
public:
    void draw() override { cout << "Drawing a rectangle" << endl; }
};

class Circle : public Shape {
public:
    void draw() override { cout << "Drawing a circle" << endl; }
};

Shape The class is a base class and declares a pure virtual function draw(). The Rectangle and Circle classes inherit from Shape and override the draw() function to implement specific drawing behavior. This allows the draw() method to be called with the Shape variable and perform the correct drawing behavior based on the actual type of the object.

Practical case:

Consider a program for managing books. You can create a

Book class to represent a book's title, author, and publication date. You can then create the FictionBook and NonFictionBook classes that extend the Book class and add additional functionality specific to each class. Using OOP principles, you can design a flexible and maintainable program to handle different types of books.

By understanding and applying OOP principles, you can write C++ code that is clear, maintainable, and reusable.

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