class f {
private $str = "123";
public function fun() {
echo $this->str;
}
}
class s extends f {
public $str = "abc";
}
$s = new s();
$s->fun();
输出:123
class f {
public $str = "123";
public function fun() {
echo $this->str;
}
}
class s extends f {
public $str = "abc";
}
$s = new s();
$s->fun();
输出:abc
第一个的输出很疑惑,为什么会输出父类的属性值?麻烦大家给我分析分析内存,有图说明更好,谢谢大家了。
回复讨论(解决方案)
私有属性不会被继承
私有属性只能用定义它的类的方法访问
私有属性不会被继承
私有属性只能用定义它的类的方法访问
这一点我还是明白,但是我疑惑的地方是,我在子类重新定义了属性,为什么调用方法还是会输出父类的属性值?
私有的是不可侵犯的
私有属性不能被子类覆盖,既然是私有属性不能被继承,当然也就不可能被覆盖了
私有的是不可侵犯的
私有属性不能被子类覆盖,既然是私有属性不能被继承,当然也就不可能被覆盖了
既然没有继承下来,我在子类定义属性也没有问题吧?然后我用继承下来的方法调用本类的属性值,为什么就拿不到呢?反而去拿父类的。不好意思,我还是很疑惑。
既然方法是继承过来的,很自然他会先在自己的地盘里寻找属性?
解释的我也不清楚。。。。
刚才百度了一下,明白了 嘿嘿 你看下 这句话
如果父类有私有的属性。那么父类的方法只为父类的私有属性服务。

PHP is a server-side scripting language used for dynamic web development and server-side applications. 1.PHP is an interpreted language that does not require compilation and is suitable for rapid development. 2. PHP code is embedded in HTML, making it easy to develop web pages. 3. PHP processes server-side logic, generates HTML output, and supports user interaction and data processing. 4. PHP can interact with the database, process form submission, and execute server-side tasks.

PHP has shaped the network over the past few decades and will continue to play an important role in web development. 1) PHP originated in 1994 and has become the first choice for developers due to its ease of use and seamless integration with MySQL. 2) Its core functions include generating dynamic content and integrating with the database, allowing the website to be updated in real time and displayed in personalized manner. 3) The wide application and ecosystem of PHP have driven its long-term impact, but it also faces version updates and security challenges. 4) Performance improvements in recent years, such as the release of PHP7, enable it to compete with modern languages. 5) In the future, PHP needs to deal with new challenges such as containerization and microservices, but its flexibility and active community make it adaptable.

The core benefits of PHP include ease of learning, strong web development support, rich libraries and frameworks, high performance and scalability, cross-platform compatibility, and cost-effectiveness. 1) Easy to learn and use, suitable for beginners; 2) Good integration with web servers and supports multiple databases; 3) Have powerful frameworks such as Laravel; 4) High performance can be achieved through optimization; 5) Support multiple operating systems; 6) Open source to reduce development costs.

PHP is not dead. 1) The PHP community actively solves performance and security issues, and PHP7.x improves performance. 2) PHP is suitable for modern web development and is widely used in large websites. 3) PHP is easy to learn and the server performs well, but the type system is not as strict as static languages. 4) PHP is still important in the fields of content management and e-commerce, and the ecosystem continues to evolve. 5) Optimize performance through OPcache and APC, and use OOP and design patterns to improve code quality.

PHP and Python have their own advantages and disadvantages, and the choice depends on the project requirements. 1) PHP is suitable for web development, easy to learn, rich community resources, but the syntax is not modern enough, and performance and security need to be paid attention to. 2) Python is suitable for data science and machine learning, with concise syntax and easy to learn, but there are bottlenecks in execution speed and memory management.

PHP is used to build dynamic websites, and its core functions include: 1. Generate dynamic content and generate web pages in real time by connecting with the database; 2. Process user interaction and form submissions, verify inputs and respond to operations; 3. Manage sessions and user authentication to provide a personalized experience; 4. Optimize performance and follow best practices to improve website efficiency and security.

PHP uses MySQLi and PDO extensions to interact in database operations and server-side logic processing, and processes server-side logic through functions such as session management. 1) Use MySQLi or PDO to connect to the database and execute SQL queries. 2) Handle HTTP requests and user status through session management and other functions. 3) Use transactions to ensure the atomicity of database operations. 4) Prevent SQL injection, use exception handling and closing connections for debugging. 5) Optimize performance through indexing and cache, write highly readable code and perform error handling.

Using preprocessing statements and PDO in PHP can effectively prevent SQL injection attacks. 1) Use PDO to connect to the database and set the error mode. 2) Create preprocessing statements through the prepare method and pass data using placeholders and execute methods. 3) Process query results and ensure the security and performance of the code.


Hot AI Tools

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

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

Undress AI Tool
Undress images for free

Clothoff.io
AI clothes remover

AI Hentai Generator
Generate AI Hentai for free.

Hot Article

Hot Tools

Atom editor mac version download
The most popular open source editor

MinGW - Minimalist GNU for Windows
This project is in the process of being migrated to osdn.net/projects/mingw, you can continue to follow us there. MinGW: A native Windows port of the GNU Compiler Collection (GCC), freely distributable import libraries and header files for building native Windows applications; includes extensions to the MSVC runtime to support C99 functionality. All MinGW software can run on 64-bit Windows platforms.

EditPlus Chinese cracked version
Small size, syntax highlighting, does not support code prompt function

Dreamweaver Mac version
Visual web development tools

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