C++ function overloading and rewriting and design principles of class hierarchy

Introduction to function overloading and rewriting Function overloading and rewriting in C allow functions of the same name to have different parameter lists or to override functions of the same name in the base class to achieve more flexible and extensible code, and to follow important principles (Such as SRP, LSP, DIP).

C Function Overloading, Rewriting and Class Hierarchy Design Principles

Introduction

Function overloading and rewriting in C are two basic concepts that are crucial to understanding and designing class-based programs. Function overloading allows a function of the same name to have a different parameter list, while function overriding allows a function in a derived class to override a function of the same name in a base class. These concepts are important for creating a flexible and scalable code base.

Function Overloading

Function overloading allows the creation of functions with the same name but accepting different parameter lists. This is useful for handling different types and amounts of input. For example, the following function can be created to add two int or two double:

int add(int a, int b) { return a + b; }
double add(double a, double b) { return a + b; }

When the compiler sees the add function call , which will match the most appropriate overloaded version.

Function overriding

Function overriding allows functions in a derived class to override functions of the same name in the base class. This is used to modify or extend base class behavior in subclasses. For example, the following base and derived classes redefine the print function:

class Base {
public:
    void print() { cout << "Base" << endl; }
};

class Derived : public Base {
public:
    void print() { cout << "Derived" << endl; }
};

When the print function in the derived class is called, it overrides the one in the base class function with the same name, thus printing "Derived".

Class Hierarchy Design Principles

When designing a class hierarchy, the following principles are very important:

• Liskov Substitution Principle (LSP): A subclass should always be able to replace its base class without changing program behavior.
• Dependency Inversion Principle (DIP): High-level modules should not depend on low-level modules, they should depend on abstractions.
• Single Responsibility Principle (SRP): Each class should be responsible for a single responsibility.

Function overloading and rewriting are critical to following these principles.

Practical Case

Consider a graphics application that needs to handle objects of different shapes. You can use the base class Shape to represent all shapes, and derived classes such as Rectangle and Circle to represent specific shapes.

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

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

class Circle : public Shape {
public:
    Circle(double radius) : radius(radius) {}
    virtual double area() override { return 3.14 * radius * radius; }
private:
    double radius;
};

The area of ​​different shapes can be easily calculated by using function rewriting. By following SRP principles, each class defines its specific responsibilities.

Conclusion

Function overloading and rewriting are powerful concepts in C, and they are essential for designing flexible and extensible code. Following class hierarchy design principles ensures the creation of robust and maintainable software.

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