在PHP中所有的报错信息可以用error_reporting()这个函数来设置:
它的参数有字符串和数字两种表示方法,共14个等级,但是呢,我看使用其他数字貌似也可以,起初我以为它指的是一定的报错区间,后来,终于发现了其中的规律:
现在,我将其总结如下:
数字 | 常量 | 说明 |
1 | E_ERROR | 致命错误,脚本执行中断,就是脚本中有不可识别的东西出现 举例: Error:Invalid parameters. Invalid parameter name |
2 | E_WARNING | 部分代码出错,但不影响整体运行 举例: Warning: require_once(E:/include/config_base.php) |
4 | E_PARSE | 字符、变量或结束的地方写规范有误 举例: Parse error: syntax error, unexpected $end in |
8 | E_NOTICE | 一般通知,如变量未定义等 举例: Notice: Undefined variable: p in E:\web\index.php on line 17 |
16 | E_CORE_ERROR | PHP进程在启动时,发生了致命性错误 举例: 暂无 |
32 | E_CORE_WARNING | 在PHP启动时警告(非致命性错误) 举例: 暂无 |
64 | E_COMPILE_ERROR | 编译时致命性错误 举例: 暂无 |
128 | E_COMPILE_WARNING | 编译时警告级错误 举例: 暂无 |
256 | E_USER_ERROR | 用户自定义的错误消息 举例: 暂无 |
512 | E_USER_WARNING | 用户自定义的警告消息 举例: 暂无 |
1024 | E_USER_NOTICE | 用户自定义的提醒消息 举例: 暂无 |
2047 | E_ALL | 以上所有的报错信息,但不包括E_STRICT的报错信息 举例: 暂无 |
2048 | E_STRICT | 编码标准化警告,允许PHP建议如何修改代码以确保最佳的互操作性向前兼容性。 |
error_reporting 变量的默认值是 E_ALL & ~E_NOTICE
开发时,最佳的值为: E_ALL | E_STRICT
如果设置为:error_reporting(E_ALL | E_STRICT),则表示记录所有的错误信息
可能会导致网站出现一大堆的错误代码;但是对于程序员来说应该说是一件好事,可以把代码优化到最优; 一些非致命性错误虽然不影响程序的运行,但是会加重PHP的负担.
最后,晒出英文版的对照表:
1 | E_ERROR | Fatal run-time errors. Errors that can not be recovered from. Execution of the script is halted |
2 | E_WARNING | Non-fatal run-time errors. Execution of the script is not halted |
4 | E_PARSE | Compile-time parse errors. Parse errors should only be generated by the parser |
8 | E_NOTICE | Run-time notices. The script found something that might be an error, but could also happen when running a script normally |
16 | E_CORE_ERROR | Fatal errors at PHP startup. This is like an E_ERROR in the PHP core |
32 | E_CORE_WARNING | Non-fatal errors at PHP startup. This is like an E_WARNING in the PHP core |
64 | E_COMPILE_ERROR | Fatal compile-time errors. This is like an E_ERROR generated by the Zend Scripting Engine |
128 | E_COMPILE_WARNING | Non-fatal compile-time errors. This is like an E_WARNING generated by the Zend Scripting Engine |
256 | E_USER_ERROR | Fatal user-generated error. This is like an E_ERROR set by the programmer using the PHP function trigger_error() |
512 | E_USER_WARNING | Non-fatal user-generated warning. This is like an E_WARNING set by the programmer using the PHP function trigger_error() |
1024 | E_USER_NOTICE | User-generated notice. This is like an E_NOTICE set by the programmer using the PHP function trigger_error() |
2048 | E_STRICT | Run-time notices. PHP suggest changes to your code to help interoperability and compatibility of the code |
4096 | E_RECOVERABLE_ERROR | Catchable fatal error. This is like an E_ERROR but can be caught by a user defined handle (see also set_error_handler()) |
8191 | E_ALL | All errors and warnings, except level E_STRICT (E_STRICT will be part of E_ALL as of PHP 6.0) |

Reasons for PHPSession failure include configuration errors, cookie issues, and session expiration. 1. Configuration error: Check and set the correct session.save_path. 2.Cookie problem: Make sure the cookie is set correctly. 3.Session expires: Adjust session.gc_maxlifetime value to extend session time.

Methods to debug session problems in PHP include: 1. Check whether the session is started correctly; 2. Verify the delivery of the session ID; 3. Check the storage and reading of session data; 4. Check the server configuration. By outputting session ID and data, viewing session file content, etc., you can effectively diagnose and solve session-related problems.

Multiple calls to session_start() will result in warning messages and possible data overwrites. 1) PHP will issue a warning, prompting that the session has been started. 2) It may cause unexpected overwriting of session data. 3) Use session_status() to check the session status to avoid repeated calls.

Configuring the session lifecycle in PHP can be achieved by setting session.gc_maxlifetime and session.cookie_lifetime. 1) session.gc_maxlifetime controls the survival time of server-side session data, 2) session.cookie_lifetime controls the life cycle of client cookies. When set to 0, the cookie expires when the browser is closed.

The main advantages of using database storage sessions include persistence, scalability, and security. 1. Persistence: Even if the server restarts, the session data can remain unchanged. 2. Scalability: Applicable to distributed systems, ensuring that session data is synchronized between multiple servers. 3. Security: The database provides encrypted storage to protect sensitive information.

Implementing custom session processing in PHP can be done by implementing the SessionHandlerInterface interface. The specific steps include: 1) Creating a class that implements SessionHandlerInterface, such as CustomSessionHandler; 2) Rewriting methods in the interface (such as open, close, read, write, destroy, gc) to define the life cycle and storage method of session data; 3) Register a custom session processor in a PHP script and start the session. This allows data to be stored in media such as MySQL and Redis to improve performance, security and scalability.

SessionID is a mechanism used in web applications to track user session status. 1. It is a randomly generated string used to maintain user's identity information during multiple interactions between the user and the server. 2. The server generates and sends it to the client through cookies or URL parameters to help identify and associate these requests in multiple requests of the user. 3. Generation usually uses random algorithms to ensure uniqueness and unpredictability. 4. In actual development, in-memory databases such as Redis can be used to store session data to improve performance and security.

Managing sessions in stateless environments such as APIs can be achieved by using JWT or cookies. 1. JWT is suitable for statelessness and scalability, but it is large in size when it comes to big data. 2.Cookies are more traditional and easy to implement, but they need to be configured with caution to ensure security.


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