Detailed explanation of C++ function inheritance: How to define and use abstract base classes?

Function inheritance allows derived classes to reuse the function definitions of the base class, which is achieved through the following steps: Define an abstract base class, including pure virtual functions. Use the override keyword in the derived class to inherit and implement the functions of the base class. Practical case: Create an abstract base class Shape, and derive classes Circle and Rectangle to calculate the areas of different shapes.

C Detailed explanation of function inheritance: defining and using abstract base classes

What is function inheritance?

Function inheritance is a C feature that allows derived classes to inherit the function definitions of a base class, thereby reusing the functionality of the base class in subclasses.

Define abstract base class

An abstract base class is a base class that is not intended to be instantiated, it only serves as a base class for other classes. It contains pure virtual functions (that is, functions without a function body) that must be overridden in derived classes. To declare an abstract base class, use virtual and = 0, for example:

class Shape {
public:
    virtual double area() const = 0;
};

Function inheritance in derived classes

A derived class can inherit the function definition of an abstract base class by using the override keyword and providing an implementation of the function. For example:

class Circle : public Shape {
public:
    override double area() const {
        return M_PI * radius * radius;
    }
private:
    double radius;
};

Practical case: Shape area calculation

Let us take the calculation of shape area as an example for a practical demonstration. We create a Shape abstract base class and create Circle and Rectangle derived classes to calculate the area of ​​circles and rectangles:

#include <iostream>
#include <cmath>

using namespace std;

class Shape {
public:
    virtual double area() const = 0;
};

class Circle : public Shape {
public:
    Circle(double radius) : radius(radius) {}
    override double area() const {
        return M_PI * radius * radius;
    }
private:
    double radius;
};

class Rectangle : public Shape {
public:
    Rectangle(double width, double height) : width(width), height(height) {}
    override double area() const {
        return width * height;
    }
private:
    double width;
    double height;
};

int main() {
    Circle circle(5);
    cout << "Circle area: " << circle.area() << endl;

    Rectangle rectangle(3, 4);
    cout << "Rectangle area: " << rectangle.area() << endl;

    return 0;
}

Run output:

Circle area: 78.5398
Rectangle area: 12

The above is the detailed content of Detailed explanation of C++ function inheritance: How to define and use abstract base classes?. For more information, please follow other related articles on the PHP Chinese website!