Found a total of 10000 related content
What are attributes and methods in Python classes?
Article Introduction：In Python, class attributes and instance attributes are used to store data related to a class or instance, while methods define the behavior of an object. ① Class attributes are shared by all instances, such as species; ② Instance attributes are specific to each object, such as name; ③ Methods are functions defined in the class, and use self to access instance data, such as bark(); ④ Class methods (@classmethod) and static methods (@staticmethod) provide flexible access to classes or instances; ⑤ Attributes and methods usually work together, such as using class attribute count to track the number of instances and output through class method total_dogs(). This structure makes object-oriented programming more organized and maintainable.
2025-06-24
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702
How to use oracle index
Article Introduction：Oracle index is a special data structure that accelerates data access and improves query performance by storing pointers to data in tables. Oracle provides a variety of index types, including B-Tree index, bitmap index, function index, and hash index. Indexes are especially suitable for data queries that require frequent filtering of specific columns or accessing large tables, but creating and maintaining indexes requires additional space and overhead, and large amounts of indexes may also reduce query efficiency.
2025-04-11
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302
How to implement array LRU cache in PHP?
Article Introduction：Implementing LRU cache in PHP can simulate bidirectional linked list structure by using associative arrays and index arrays. The specific steps are as follows: 1. Create an LRUCache class and initialize an array of capacity, cache and access order. 2. Implement the get method, return the value and update the access order. 3. Implement the put method, add or update elements, and remove the longest-lasting elements if necessary. This method is simple and easy to understand, but performance may decline under large data volumes.
2025-05-23
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667
Can you explain classes and objects in C with an example?
Article Introduction：In C, a class is a user-defined data type, containing data and functions, and an object is an instance of a class. Classes are like blueprints, which define the structure and behavior of objects. For example, classCar defines the brand, model, year and methods of starting the engine; objects are specific examples created based on the blueprint, such as myCar and yourCar represent different car objects and have their own data copies. Using classes and objects can improve the organization, reusability, abstraction and maintainability of the code, and is suitable for scenarios such as player character modeling in game development. In addition, the access modifier controls member access rights, the constructor is used to initialize objects, and the class also supports inheritance to build a hierarchy.
2025-06-29
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315
php pdo operation database, phppdo database_PHP tutorial
Article Introduction：php pdo operates the database, phppdo database. php pdo operates the database, and the phppdo database POD extension was added in PHP5. This extension provides the PHP built-in class PDO to access the database. Different databases use the same method name to solve data problems.
2016-07-12
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1028
Python class method vs static method
Article Introduction：The main difference between classmethod and staticmethod is parameter passing and purpose. ① Classmethod receives the class as the first parameter (cls), which can be used to access class properties and methods, which are suitable for factory methods or class-level operations; ② Staticmethod does not receive automatically passed parameters, but is more like an ordinary function bound to a class, suitable for tool functions or logical encapsulation; ③ Classmethod supports inheritance and rewrite and can return subclass instances, and although staticmethod also supports rewrite, it does not involve class or instance state; ④ If the method needs to call the class itself data, select classmethod. If it is only logical classification and has no class structure, select staticme
2025-07-04
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948
Deep Dive into Python's Object-Oriented Programming Concepts
Article Introduction：Python's object-oriented programming organizes code through classes and objects, emphasizing the combination of data and operations. 1. The class is a template, the object is an instance, and the attributes are initialized with init; 2. Inherit the reusable class function and use super() to call the parent class; 3. Encapsulate the control of access rights through underscore or double underscore to protect the internal state; 4. Polymorphism allows different classes to implement the same-name method and unify the different behaviors of the interface. These features make the program structure clear and easy to maintain.
2025-07-06
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610
How do abstract classes differ from interfaces in PHP, and when would you use each?
Article Introduction：Abstract classes and interfaces have their own uses in PHP. 1. Abstract classes are used to share code, support constructors and control access, and include abstract methods and concrete methods. 2. The interface is used to define behavior contracts. All methods must be implemented and are public by default, and support multiple inheritance. 3. Since PHP8, the interface can contain default methods to implement, but there is still no constructor or state. 4. When using abstract classes, you need to encapsulate implementation details; when using interfaces, you need to define cross-class behavior or build plug-in systems. 5. Can be used in combination: abstract classes implement interfaces or combine multiple interfaces into one abstract class. Select whether the structure plus sharing behavior (abstract class) or only the structure (interface).
2025-06-04
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1105
Introduction to Linked Lists in PHP: A Beginner&#s Guide
Article Introduction：The linked list is a basic data structure in computer science. Its elements (referred to as nodes) are connected in turn by pointer. Different from the array, the linked list is dynamic, which means that their size can grow or shrink without the need to adjust the size operation. This tutorial will introduce the basic knowledge of the linked list in PHP.
The structure of the linked list node
Each node in the linked list consists of two parts:
Data: The value stored in the node.
Next: Reference (pointer) to the next node.
The following is an example of implementing basic nodes in PHP:
class node {
public $ data;
public $ night;
public function
2025-01-26
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1011
C tutorial for C programmers
Article Introduction：This article provides developers familiar with C language with key points to quickly get started with C. 1. Classes and objects: C's class is an upgrade of the C structure, supports encapsulating data and methods, and introduces access control characters private and public. 2. Constructor and destructor: Implement automatic object initialization and resource release. The constructor has no return type. It is recommended to use an initialization list. 3.STL: The standard template library provides efficient containers such as vector, map, and set, simplifying common data structure operations. 4. Namespace and input and output: Use cin/cout instead of scanf/printf to avoid name conflicts through namespace. Master these core contents and write practical C programs
2025-06-27
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247
How to implement MVC mode in PHP?
Article Introduction：Implementing MVC pattern in PHP can use the following steps: 1. Define the model class, such as the Article class to process article data. 2. Create a view file, such as article_list.php to display the article list. 3. Write a controller, such as ArticleController, to process requests and coordinate models and views. 4. Implement the routing mechanism to map requests to controller methods. Through these steps, a clear structure and easy-to-maintain web application can be built.
2025-05-23
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579
How do I use the MVC (Model-View-Controller) architectural pattern in PHP?
Article Introduction：How to use MVC mode in PHP? 1. Set the basic file structure and create three folders: Model, View and Controller; 2. Write model processing logic, such as UserModel class operating database; 3. Create controller to receive requests and coordinate model and view, such as UserController obtaining data; 4. Build view display content, such as user_profile.php mixing HTML and PHP output dynamic data; 5. Unified request processing through the front-end controller index.php, loading the model and controller and executing corresponding methods to achieve application scalability.
2025-06-21
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753
How do I create objects from classes in PHP?
Article Introduction：To create an object in PHP, you must first define the class and then instantiate it with the new keyword. 1. Classes are blueprints of objects, defining attributes and methods; 2. Create object instances using new; 3. Constructors are used to initialize different data; 4. Access attributes and methods through ->; 5. Pay attention to access control of public, private, and protected; 6. Multiple independent instances can be created, each maintaining its status. For example, after defining the Car class, newCar('red') creates an object and passes a parameter, $myCar->startEngine() calls the method, and each object does not affect each other. Mastering these helps build clearer, scalable applications.
2025-06-24
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846
