Quick Tip: How to Manage Error Reporting in PHP

This article will explore the skills of PHP error reporting and introduce how to use PHP tools to handle errors in a controllable way, thereby saving debugging time.

PHP is essentially a "lightweight exception" programming language. This means that, while it supports exception handling, the script continues to execute unless a fatal error occurs, no matter what happens.

Example:

<code class="language-php"><?php   echo $sitepoint;</code>

The above code will return the following message:

<code>Notice: Undefined variable: sitepoint in PHP shell code on line 1</code>

PHP will only throw a notification error and continue to execute happily. "Heavyweight Exception" languages ​​(such as Python) throw an error and stop execution.

Therefore, PHP developers must take extra care when writing code. Unexpected results may occur during program execution because notifications will not stop executing, but may affect the correct behavior of the program.

Before introducing how to adjust the PHP error reporting style, let's first understand several levels of PHP error severity.

PHP has three main types of messages: error, notification, and warning. They represent different severity levels: E_ERROR, E_NOTICE, and E_WARNING.

• Errors are fatal runtime errors, usually caused by failures in the code. This will cause PHP to stop execution.
• Notification is caused by code that may or cannot cause problems (e.g., undefined variables). These do not cause execution to stop.
• Warning is a fatal error, script execution will not stop.

Error logging in PHP

By default, PHP does not log any errors. To do this, we have to open the display_errors variable in the PHP configuration file (php.ini file) to explicitly indicate it to start logging.

In this file, we can also tell PHP whether we want to log notifications and warnings, and where this log should be logged.

can also trigger logging in the code. To do this, we can use the error_log() function. Since error logging is not the focus of this article, please see here for more information.

Change PHP Error Report

We can use the error_reporting() function to change the default PHP error reporting behavior. Using this function, we can set the error level of the script duration. This is done by passing one or more predefined error constants to the function.

For example, if we want to see not only errors but also notifications, we can use:

<code class="language-php"><?php error_reporting(E_ERROR | E_NOTICE);</code>

With this declaration, script execution will not only stop when an error occurs, but also when a notification occurs.

Suppress error

We can also use the error control operator (@) to tell PHP to suppress specific errors. By placing this operator at the beginning of an expression, any errors that are the direct result of the expression will be silently processed:

<code class="language-php"><?php echo @$sitepoint;</code>

If $sitepoint exists, this outputs the value of $sitepoint, but if it does not exist, it returns NULL and does not print anything (rather than throwing a notification).

Be very careful when using this operator, as it will completely hide the error. Not only will the error not be displayed, but it will not be sent to the error log. While this seems harmless, using this operator masks deeper structural problems in the code and masks potentially wrong behavior.

Use PHP as the "heavyweight exception" language

Finally, PHP can also be used as a "heavyweight exception" programming language. A normal PHP error can be thrown as an exception using the ErrorException class that extends the PHP Exception class.

In the following example, the user-defined function errorhandler() is set as an error handler, using the set_error_handler() function. When a fatal error occurs because the file_get_contents() function cannot find the file, it throws an ErrorException:

Using this method we can handle execution errors like we do with exceptions, wrap them in a try…catch statement, and provide appropriate instructions on how to do it in this case.

<code class="language-php"><?php   echo $sitepoint;</code>

Conclusion

All in all, PHP may handle errors in a very loose way. It depends on our developers using existing tools to handle them better so that we can make the most of the language. By using this set of tools, we can handle errors in a controlled manner, saving debugging time.

Frequently Asked Questions about Managing Error Reports in PHP

What is a bug report in PHP?

Error reporting in PHP refers to the process of detecting and handling errors or exceptions that occur during PHP code execution. Errors may include syntax errors, runtime errors, and logical errors.

How to enable error reporting in PHP?

You can enable error reporting in PHP by setting the error_reporting configuration directive in PHP script or php.ini configuration file. You can also use the error_reporting function to dynamically change the reporting level in your code.

How to handle PHP errors gracefully?

You can handle the error gracefully by using the try...catch block and use the conditional statement to check the error condition before continuing to execute the code.

What is the PHP trigger_error function?

The trigger_error function is used to generate user-level error messages. You can use this function to create custom error messages and trigger them in your code.

How to log PHP errors for debugging and analysis?

You can use the error_log function to log PHP errors to a file. Additionally, you can configure PHP to log errors to a specific file by modifying the error_log directive in the php.ini configuration.

The above is the detailed content of Quick Tip: How to Manage Error Reporting in PHP. For more information, please follow other related articles on the PHP Chinese website!