The secret of C++ virtual functions revealed
Apr 19, 2024 am 09:18 AMVirtual functions use dynamic binding to determine the function to be called at runtime to achieve polymorphism. Its advantages include scalability and reusability, but it also introduces overhead and complexity. Virtual functions are often used to implement methods of different types of objects in a uniform way.
The secret of C virtual functions revealed
Virtual functions are a powerful tool in C that allow you to create methods that can be overridden by derived classes. This means you can write base class code and then customize it as needed in the derived classes.
How virtual functions work
Virtual functions use a technology called dynamic binding (also known as late binding). Unlike static binding (also known as early binding), which determines the function to be called at compile time, dynamic binding is determined at runtime.
This means that when you call a virtual function, the compiler generates a pointer to the virtual function table. This table contains pointers to functions implemented by each derived class. At run time, this pointer is used to select the function to call.
Advantages of virtual functions
Advantages of virtual functions include:
- Extensibility:You can add new functionality to existing code , without having to modify the base class code.
- Reusability: You can share common code while still allowing derived classes to customize behavior.
- Polymorphism: Virtual functions are the basis for achieving polymorphism, so objects can call methods in a uniform way, even if they are objects of different types.
Disadvantages of virtual functions
Virtual functions also have some disadvantages, including:
- ##Overhead:Create and look up the virtual function table It will bring some runtime overhead.
- Complexity: Understanding and debugging the code for virtual functions can be complex.
class Shape { public: virtual double area() = 0; // 純虛函數(shù) virtual double perimeter() = 0; // 純虛函數(shù) }; class Circle : public Shape { public: Circle(double radius) : _radius(radius) {} double area() override { return M_PI * _radius * _radius; } double perimeter() override { return 2 * M_PI * _radius; } private: double _radius; }; class Square : public Shape { public: Square(double side) : _side(side) {} double area() override { return _side * _side; } double perimeter() override { return 4 * _side; } private: double _side; }; int main() { Shape* shapes[] = { new Circle(5), new Square(3) }; for (Shape* shape : shapes) { std::cout << "Area: " << shape->area() << std::endl; std::cout << "Perimeter: " << shape->perimeter() << std::endl; } delete[] shapes; return 0; }In this example, the
Shape class declares two pure virtual functions
area() and
perimeter().
Circle and
Square derived classes override these functions, providing specific implementations for each shape.
main() The function uses dynamic binding to call different virtual functions, depending on the type of the current object. This allows us to use a unified interface to handle different shapes.
The above is the detailed content of The secret of C++ virtual functions revealed. For more information, please follow other related articles on the PHP Chinese website!

Hot AI Tools

Undress AI Tool
Undress images for free

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Clothoff.io
AI clothes remover

Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Article

Hot Tools

Notepad++7.3.1
Easy-to-use and free code editor

SublimeText3 Chinese version
Chinese version, very easy to use

Zend Studio 13.0.1
Powerful PHP integrated development environment

Dreamweaver CS6
Visual web development tools

SublimeText3 Mac version
God-level code editing software (SublimeText3)

Hot Topics

People who study Python transfer to C The most direct confusion is: Why can't you write like Python? Because C, although the syntax is more complex, provides underlying control capabilities and performance advantages. 1. In terms of syntax structure, C uses curly braces {} instead of indentation to organize code blocks, and variable types must be explicitly declared; 2. In terms of type system and memory management, C does not have an automatic garbage collection mechanism, and needs to manually manage memory and pay attention to releasing resources. RAII technology can assist resource management; 3. In functions and class definitions, C needs to explicitly access modifiers, constructors and destructors, and supports advanced functions such as operator overloading; 4. In terms of standard libraries, STL provides powerful containers and algorithms, but needs to adapt to generic programming ideas; 5

C destructorsarespecialmemberfunctionsthatautomaticallyreleaseresourceswhenanobjectgoesoutofscopeorisdeleted.1)Theyarecrucialformanagingmemory,filehandles,andnetworkconnections.2)Beginnersoftenneglectdefiningdestructorsfordynamicmemory,leadingtomemo

C STL is a set of general template classes and functions, including core components such as containers, algorithms, and iterators. Containers such as vector, list, map, and set are used to store data. Vector supports random access, which is suitable for frequent reading; list insertion and deletion are efficient but accessed slowly; map and set are based on red and black trees, and automatic sorting is suitable for fast searches. Algorithms such as sort, find, copy, transform, and accumulate are commonly used to encapsulate them, and they act on the iterator range of the container. The iterator acts as a bridge connecting containers to algorithms, supporting traversal and accessing elements. Other components include function objects, adapters, allocators, which are used to customize logic, change behavior, and memory management. STL simplifies C

In C, cin and cout are used for console input and output. 1. Use cout to read the input, pay attention to type matching problems, and stop encountering spaces; 3. Use getline(cin, str) when reading strings containing spaces; 4. When using cin and getline, you need to clean the remaining characters in the buffer; 5. When entering incorrectly, you need to call cin.clear() and cin.ignore() to deal with exception status. Master these key points and write stable console programs.

InheritanceinC allowsaderivedclasstoinheritpropertiesandbehaviorsfromabaseclasstopromotecodereuseandreduceduplication.Forexample,classeslikeEnemyandPlayercaninheritsharedfunctionalitysuchashealthandmovementfromabaseCharacterclass.C supportssingle,m

FunctionhidinginC occurswhenaderivedclassdefinesafunctionwiththesamenameasabaseclassfunction,makingthebaseversioninaccessiblethroughthederivedclass.Thishappenswhenthebasefunctionisn’tvirtualorsignaturesdon’tmatchforoverriding,andnousingdeclarationis

volatile tells the compiler that the value of the variable may change at any time, preventing the compiler from optimizing access. 1. Used for hardware registers, signal handlers, or shared variables between threads (but modern C recommends std::atomic). 2. Each access is directly read and write memory instead of cached to registers. 3. It does not provide atomicity or thread safety, and only ensures that the compiler does not optimize read and write. 4. Constantly, the two are sometimes used in combination to represent read-only but externally modifyable variables. 5. It cannot replace mutexes or atomic operations, and excessive use will affect performance.

There are mainly the following methods to obtain stack traces in C: 1. Use backtrace and backtrace_symbols functions on Linux platform. By including obtaining the call stack and printing symbol information, the -rdynamic parameter needs to be added when compiling; 2. Use CaptureStackBackTrace function on Windows platform, and you need to link DbgHelp.lib and rely on PDB file to parse the function name; 3. Use third-party libraries such as GoogleBreakpad or Boost.Stacktrace to cross-platform and simplify stack capture operations; 4. In exception handling, combine the above methods to automatically output stack information in catch blocks
