PHP (Hypertext Preprocessor) is a scripting language widely used for web development. Error handling and debugging are considered to be a very important piece when developing PHP applications. Foreign programmers have accumulated many PHP error handling and debugging skills through experience. Here are some common and practical skills.

1. Error reporting level modification
   In PHP, specific types of PHP errors can be displayed or suppressed by modifying the error reporting level. By setting the error reporting level to "E_ALL", all types of PHP errors can be displayed.

   error_reporting(E_ALL);

When setting the error reporting level, developers can use the following constants:

• E_ERROR: Fatal Error
• E_WARNING: A warning that does not affect program execution
• E_NOTICE: A warning that does not affect program execution, but there are potential problems
• E_PARSE: Parsing error
• E_DEPRECATED : Deprecated code reminder
• E_STRICT: Code standards reminder

Developers can choose the level of error reporting that needs to be displayed based on the specific needs of the project. At the same time, in a production environment, the error reporting level should be set to E_ERROR, and all other types of errors should be suppressed.

2. Error logging
   In the PHP development process, error logging is very important. By recording error logs, problems can be discovered and solved in time. We can log errors to the specified file by modifying the error_log option in the php.ini file. This option supports two different values:

• error_log = /path/to/log.file: Log errors to the /path/to/log.file file.
• error_log = syslog: Record errors to the system log.

At the same time, you can also log errors to the specified file by calling the error_log() function in the code:

error_log('Error message', 3, '/path/ to/log/file');

3. Breakpoint debugging
   Breakpoint debugging is a very common debugging method. In mature IDE tools such as PHPStorm, you can debug code by adding breakpoints, pausing code execution, viewing variable values ??and function execution processes. When the development environment does not have an IDE, you can use PHP extensions such as xdebug to implement breakpoint debugging. This can be achieved through the following three steps:

• Install and configure the xdebug extension
• Add breakpoints in the code
• Start xdebug and wait for the IDE to connect

4. Debug output
   Using debug output functions such as echo or var_dump, developers can output variable values ??and debugging information when the code is executed. However, in a production environment, this information should be disabled or deleted. Otherwise, an attacker can use this information to compromise the application.

In the development environment, these functions can be enabled or disabled by using the ini_set() function.

ini_set('display_errors', 'On');
ini_set('html_errors', 'On');

At the same time, similar to breakpoint debugging, third parties can also be used Class libraries, such as Kint, DebugBar, etc. to debug output.

5. Using exception handling
   Exception handling is a relatively standard and standardized error handling method. By throwing exceptions, errors can be efficiently handled during code execution. Exceptions can be caught, handled, logged, and re-thrown if necessary. This makes the code clearer and more predictable, easier to maintain and debug.

   try {
   //Throw exception
   throw new Exception('Error Message');
   } catch (Exception $e) {
   //Record and handle exception
   error_log($e->getMessage());
   }

By using exception handling, error handling and code can be separated, making the code easy to expand and transplant.

Summary
PHP error handling and debugging are critical parts of developing PHP applications. By using technologies such as error reporting level modification, error logging, breakpoint debugging, debugging output, and exception handling, developers can discover, locate, and solve problems faster. Foreign programmers have accumulated many PHP error handling and debugging skills through experience, and these skills can provide useful guidance and reference for our development work.

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