Summary of commonly used PHP system constants_PHP tutorial-PHP Tutorial-php.cn

Home

Backend Development

PHP Tutorial

Summary of commonly used PHP system constants_PHP tutorial

WBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWB

Jul 15, 2016 pm 01:33 PM

filelinephpCommonly usedconstantSummarizedocumentfile nameusesystem

The following are some commonly used PHP system constants:

__FILE__ current PHP file name

__LINE__ in the current PHP file Number of lines

__FUNCTION__ Currently executed function

__CLASS__ Currently executed class

PHP_VERSION PHP version

PHP_OS Current server operating system

TRUE Same as true

FALSE Same as false

E_ERROR Go to the nearest error location

E_WARNING Go to the nearest warning location

E_PARSE Syntax error There is an exception in

E_NOTICE in PHP language

M__PI Pi

M__E Scientific constant e

M__LOG2E Logarithm of e with base 2

M_LOG10E The logarithm of e with base 10

M_LN2 The natural logarithm of 2

M_LN10 The natural logarithm of 10

The content of PHP system constants is introduced Here, I hope it will be helpful to everyone.

Statement

The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn

How can you prevent session fixation attacks?Apr 28, 2025 am 12:25 AM

Effective methods to prevent session fixed attacks include: 1. Regenerate the session ID after the user logs in; 2. Use a secure session ID generation algorithm; 3. Implement the session timeout mechanism; 4. Encrypt session data using HTTPS. These measures can ensure that the application is indestructible when facing session fixed attacks.

How do you implement sessionless authentication?Apr 28, 2025 am 12:24 AM

Implementing session-free authentication can be achieved by using JSONWebTokens (JWT), a token-based authentication system where all necessary information is stored in the token without server-side session storage. 1) Use JWT to generate and verify tokens, 2) Ensure that HTTPS is used to prevent tokens from being intercepted, 3) Securely store tokens on the client side, 4) Verify tokens on the server side to prevent tampering, 5) Implement token revocation mechanisms, such as using short-term access tokens and long-term refresh tokens.

What are some common security risks associated with PHP sessions?Apr 28, 2025 am 12:24 AM

The security risks of PHP sessions mainly include session hijacking, session fixation, session prediction and session poisoning. 1. Session hijacking can be prevented by using HTTPS and protecting cookies. 2. Session fixation can be avoided by regenerating the session ID before the user logs in. 3. Session prediction needs to ensure the randomness and unpredictability of session IDs. 4. Session poisoning can be prevented by verifying and filtering session data.

How do you destroy a PHP session?Apr 28, 2025 am 12:16 AM

To destroy a PHP session, you need to start the session first, then clear the data and destroy the session file. 1. Use session_start() to start the session. 2. Use session_unset() to clear the session data. 3. Finally, use session_destroy() to destroy the session file to ensure data security and resource release.

How can you change the default session save path in PHP?Apr 28, 2025 am 12:12 AM

How to change the default session saving path of PHP? It can be achieved through the following steps: use session_save_path('/var/www/sessions');session_start(); in PHP scripts to set the session saving path. Set session.save_path="/var/www/sessions" in the php.ini file to change the session saving path globally. Use Memcached or Redis to store session data, such as ini_set('session.save_handler','memcached'); ini_set(

How do you modify data stored in a PHP session?Apr 27, 2025 am 12:23 AM

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

Give an example of storing an array in a PHP session.Apr 27, 2025 am 12:20 AM

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.

How does garbage collection work for PHP sessions?Apr 27, 2025 am 12:19 AM

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.

See all articles