php change error level

When developing with PHP, we often encounter various errors. These error messages usually help us quickly troubleshoot and solve problems in the code. However, in a production environment, we may not want to expose these errors to users. To this end, PHP provides error level control functions, allowing us to freely control how errors are displayed.

PHP’s error levels are divided into 8 levels, which are:

1. E_ERROR: Fatal error, must be resolved, otherwise the code cannot continue to execute;
2. E_WARNING: Warning errors, which will not cause the code to stop execution, but need to be repaired;
3. E_PARSE: syntax parsing errors, usually caused by code syntax errors;
4. E_NOTICE: notification errors, which will not cause the code to stop Execution, but needs to be fixed;
5. E_CORE_ERROR: Kernel fatal error, such as the error that occurs during PHP kernel initialization;
6. E_CORE_WARNING: Kernel warning error;
7. E_COMPILE_ERROR: Compilation fatal error , for example, the included file does not exist, etc.;
8. E_COMPILE_WARNING: Compilation warning error.

The default error level of PHP is E_ALL, which means all levels of error prompts are enabled. This level is very useful when developing and helps us find and resolve bugs as early as possible. But in a production environment, we usually don't want to expose error information to users. In this case, we can control the error information by changing the error level.

There are two ways to change the error level: use the ini_set function for configuration in the code, or modify the PHP configuration file php.ini. The following is an introduction to the two methods.

1. Use the ini_set function to change the error level

The ini_set function allows us to temporarily change PHP configuration items in the code. We can use this function to change the error level of PHP. The following code example demonstrates how to set the error level to E_ALL & ~E_NOTICE & ~E_WARNING, that is, turn off notifications and warning prompts:

// 设置错误级别为E_ALL & ~E_NOTICE & ~E_WARNING
ini_set('error_reporting', E_ALL & ~E_NOTICE & ~E_WARNING);

// 执行代码
echo $undefinedVariable;

In the above code, we first use the ini_set function to set the error level to E_ALL & ~E_NOTICE & ~E_WARNING, and then intentionally accessed an undefined variable $undefinedVariable. Since we have turned off notifications and warnings, PHP will not prompt us with the notice error Undefined variable: undefinedVariable. However, if we set the error level to E_ALL, PHP will throw the following error when accessing an undefined variable:

Notice: Undefined variable: undefinedVariable in /path/to/file.php on line 5

Therefore, by changing the error level, we can control whether PHP displays certain types of error message.

2. Modify the PHP configuration file php.ini to change the error level

In addition to using the ini_set function to configure the error level in the code, we can also do it in the php.ini configuration file configuration. The php.ini configuration file takes effect for the entire PHP system, and the values ​​in the configuration items can be accessed in each PHP file. The following are the configuration items related to the error level in the php.ini configuration file:

; 显示所有错误
error_reporting = E_ALL

; 显示 E_NOTICE、E_WARNING 和 E_ERROR 级别的错误
error_reporting = E_ERROR | E_WARNING | E_NOTICE

; 显示所有错误，除了 E_NOTICE 级别的错误
error_reporting = E_ALL & ~E_NOTICE

In order to protect the production environment, we usually set the error level to E_ALL & ~E_NOTICE & ~E_WARNING. This will turn off notifications and warnings and only show fatal errors and parsing errors.

Summary

During the development process, we want to find and solve errors as early as possible, so it is very useful to turn on prompts for all error levels by default. However, in a production environment, we usually don't want error messages to be exposed to users, so we need to change the error level to control how the error messages are displayed. We can achieve this function through the ini_set function or modify the PHP configuration file php.ini. In actual use, we should flexibly configure the error level according to actual needs to facilitate timely error troubleshooting and resolution.

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