求教!PHP面向对象学习
最近在学习PHP面向对象编程的过程中,遇到了些许麻烦,想劳烦大神们为我解答下。
1、类中的静态变量,使用静态变量可以减少资源的使用。那么静态变量应该用在什么情况下呢?它与全局变量的异同点又是什么呢?~(这个让我很迷茫)。
2、类中的常量。在类中定义的常量与在非类中定义的常量又有什么优缺点呢?~在什么样的情况下需要定义常量呢?~
3、有没有较好的PHP面向对象实例,可以进行学习呢?~若有,请给出相关链接。(不是要基础的学习,是要稍微深入的类实例)
在此,谢谢各位大神了。!!
------解决方案--------------------
《PHP高级程序设计:模式、框架与测试 (高清中文PDF版)》
http://www.verycd.com/topics/2783113/
------解决方案--------------------
类中的静态变量,使用静态变量可以减少资源的使用。那么静态变量应该用在什么情况下呢?它与全局变量的异同点又是什么呢?
可以减少资源的使用?
我的理解是(分两方面):
0.类的静态变量分为“类本身的静态变量”(属于类),类方法的静态变量(属于类,但是定义的位置不一样)。
1.(存储空间)静态变量它属于整个类,这样实例化很多对象的时候就可以省下内存。
2.(运算时间)从底层来讲寻址实例变量花的时间要比类静态变量要少一点,但是类方法的静态变量那就不知道(牛人帮忙解答一下)。
什么情况下使用?
1.(属于类的静态变量)比如一个Person类你想记录实例化了多少个实例那用类的静态变量就能满足。(如一个地方有多少人口:__construct的时候加一个,__destruct的时候减一个)
2.(属于类的方法的静态变量)这种情况主要的“上下文相关”的时候(即本函数上次执行结果会直接或者间接影响本次执行结果的,如四则运算)。
它与全局变量的异同点又是什么呢?
全局变量顾名思义是全局的。面向对象编程很大的目的是为了实现“高内聚,低耦合”。就比如说人口总数$count 如果用全局变量那么下次碰到这个总数,那个总数的时候改动就大了;有时候代码很可能不是你一个人写的其它人要是也用了这个变量,那岂不是杯具了。。。但是如果使用类静态变量这个问题就不会有问题(至少每个类有自己的$count)
类中的常量。在类中定义的常量与在非类中定义的常量又有什么优缺点呢?
类中定义的常量与在非类中定义的常量区别顾名思义就是使用的范围,比如性别
Person::GENDER_MALE = '男'
Person::GENDER_FEMALE = '女'
Chicken::GENDER_MALE = '公'
Chicken::GENDER_FEMALE = '母'
Cat::GENDER_MALE = '雄'
Cat::GENDER_FEMALE = '雌'
如果定义在全局中定义这两个常量就照顾的不是那么周到了。
在什么样的情况下需要定义常量呢?
比如人的性别,动物的雌雄等等。如果不定义一个常量就用0
------解决方案--------------------
1 ,male
------解决方案--------------------
female万一male打错了变成mela那不是挺杯具的??而且假设某一天你想把用01表示改为用male和female表示那你要在搜索千万行代码。如果用常量不就是改一下定义的地方就好了。。。
#! /usr/bin/php<br> <?php <br /> class Person{<br> <br> public static $count = 0; ### 记录类的实例数量<br> const GENDER_MALE = 'male';<br> const GENDER_FEMALE = 'female';<br> <br> private $_gender = self::GENDER_MALE;<br> private $_name = 'noname';<br> <br> public function setName($name){<br> $this->_name = $name;<br> return $this;<br> }<br> <br> public function __construct($name='' , $gender=self::GENDER_MALE){<br> self::$count++;<br> $this->_name = $name;<br> $this->_genger = $gender;<br> }<br> <br> public function __destruct(){<br> self::$count--;<br> }<br> <br> public function calc($action='add' , $num=1){<br> static $sum = 0;<br> <br> if($action == 'add'){<br> $sum += $num;<br> }else if($action == 'sub'){<br> $sum -= $num; <div class="clear"> </div>

TomodifydatainaPHPsession,startthesessionwithsession_start(),thenuse$_SESSIONtoset,modify,orremovevariables.1)Startthesession.2)Setormodifysessionvariablesusing$_SESSION.3)Removevariableswithunset().4)Clearallvariableswithsession_unset().5)Destroythe

Arrays can be stored in PHP sessions. 1. Start the session and use session_start(). 2. Create an array and store it in $_SESSION. 3. Retrieve the array through $_SESSION. 4. Optimize session data to improve performance.

PHP session garbage collection is triggered through a probability mechanism to clean up expired session data. 1) Set the trigger probability and session life cycle in the configuration file; 2) You can use cron tasks to optimize high-load applications; 3) You need to balance the garbage collection frequency and performance to avoid data loss.

Tracking user session activities in PHP is implemented through session management. 1) Use session_start() to start the session. 2) Store and access data through the $_SESSION array. 3) Call session_destroy() to end the session. Session tracking is used for user behavior analysis, security monitoring, and performance optimization.

Using databases to store PHP session data can improve performance and scalability. 1) Configure MySQL to store session data: Set up the session processor in php.ini or PHP code. 2) Implement custom session processor: define open, close, read, write and other functions to interact with the database. 3) Optimization and best practices: Use indexing, caching, data compression and distributed storage to improve performance.

PHPsessionstrackuserdataacrossmultiplepagerequestsusingauniqueIDstoredinacookie.Here'showtomanagethemeffectively:1)Startasessionwithsession_start()andstoredatain$_SESSION.2)RegeneratethesessionIDafterloginwithsession_regenerate_id(true)topreventsessi

In PHP, iterating through session data can be achieved through the following steps: 1. Start the session using session_start(). 2. Iterate through foreach loop through all key-value pairs in the $_SESSION array. 3. When processing complex data structures, use is_array() or is_object() functions and use print_r() to output detailed information. 4. When optimizing traversal, paging can be used to avoid processing large amounts of data at one time. This will help you manage and use PHP session data more efficiently in your actual project.

The session realizes user authentication through the server-side state management mechanism. 1) Session creation and generation of unique IDs, 2) IDs are passed through cookies, 3) Server stores and accesses session data through IDs, 4) User authentication and status management are realized, improving application security and user experience.


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

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

Hot Article

Hot Tools

Dreamweaver Mac version
Visual web development tools

SecLists
SecLists is the ultimate security tester's companion. It is a collection of various types of lists that are frequently used during security assessments, all in one place. SecLists helps make security testing more efficient and productive by conveniently providing all the lists a security tester might need. List types include usernames, passwords, URLs, fuzzing payloads, sensitive data patterns, web shells, and more. The tester can simply pull this repository onto a new test machine and he will have access to every type of list he needs.

mPDF
mPDF is a PHP library that can generate PDF files from UTF-8 encoded HTML. The original author, Ian Back, wrote mPDF to output PDF files "on the fly" from his website and handle different languages. It is slower than original scripts like HTML2FPDF and produces larger files when using Unicode fonts, but supports CSS styles etc. and has a lot of enhancements. Supports almost all languages, including RTL (Arabic and Hebrew) and CJK (Chinese, Japanese and Korean). Supports nested block-level elements (such as P, DIV),

SublimeText3 English version
Recommended: Win version, supports code prompts!

VSCode Windows 64-bit Download
A free and powerful IDE editor launched by Microsoft
