The key to debugging PHP code is to enable error prompts, use variable output tools, record logs, and use professional debugging tools. First, enable error display at the beginning of the code or modify the php.ini configuration to obtain detailed error reporting information; second, use var_dump and print_r to assist in viewing variable content, and combine the

 tag to improve readability; then, write debug information to the log file through error_log or file_put_contents, which is suitable for AJAX or command line scenarios; finally, introduce Xdebug extensions and cooperate with IDEs such as PHPStorm to implement breakpoint debugging and performance analysis, or use framework tools such as Laravel Telescope/Symfony Profiler to improve efficiency. Mastering these methods can systematically locate problems and effectively solve debugging problems in PHP development. <p><img src="/static/imghw/default1.png" data-src="https://img.php.cn/upload/article/000/000/000/175104445497498.jpg" class="lazy" alt="How to debug PHP code?"></p><p> Debugging PHP code is actually not difficult. The key is to master several commonly used methods and flexibly use them according to the specific situation. The most core idea is: <strong>locate the problem and gradually narrow the scope</strong> . </p><img src="/static/imghw/default1.png" data-src="https://img.php.cn/upload/article/000/000/000/175104445610846.jpeg" class="lazy" alt="How to debug PHP code?"><hr><h3> Turn on the error message and see the real problem</h3><p> Many times, PHP errors are turned off by default, which causes the page to be blank or jump exception, and there is no idea where the error occurred. The first step at this time should be: </p><img src="/static/imghw/default1.png" data-src="https://img.php.cn/upload/article/000/000/000/175104445726946.jpeg" class="lazy" alt="How to debug PHP code?">

• At the beginning of the code:

   ini_set('display_errors', 1);
  ini_set('display_startup_errors', 1);
  error_reporting(E_ALL);

• Or modify the configuration in php.ini :

   display_errors = On
  error_reporting = E_ALL

In this way, you can directly see error messages in the browser, such as syntax errors, undefined variables, calling non-existent methods, etc. This step is very basic but extremely important and can help you quickly eliminate low-level errors.

Use var_dump and print_r to assist in troubleshooting

If you already know where the problem is probably happening, but are not sure about the value or structure of the variable, you can use:

• var_dump($variable); ——View variable types and contents
• print_r($array); —— More suitable for printing array structures

It is recommended to use it with the <pre class="brush:php;toolbar:false">&lt;/code&gt; tag to make the output clearer:&lt;/p&gt;&lt;pre class='brush:php;toolbar:false;'&gt; echo &amp;#39;&lt;pre class=&quot;brush:php;toolbar:false&quot;&gt;&amp;#39;; print_r($data); echo &amp;#39;</pre>&#39;;</pre><p> However, note that these are just temporary debugging methods. Remember to delete or comment out before going online to avoid exposing sensitive information.</p><hr /><h3 id="Logging-instead-of-direct-output"> Logging instead of direct output</h3><p> Sometimes you cannot directly output content (such as AJAX requests, command-line scripts). At this time, logging should be used instead of <code>echo and var_dump :

 error_log(print_r($data, true));

You can also write to custom log files:

 file_put_contents('debug.log', print_r($data, true), FILE_APPEND);

This method will not affect the user interface, and can also retain debugging information for subsequent analysis.

Improve efficiency with debugging tools

For slightly more complex projects, manually adding var_dump is troublesome. Consider using some debugging tools to improve efficiency:

• Xdebug : A powerful PHP debugging extension that supports breakpoint debugging, stack trace, performance analysis and other functions
• PHPStorm Xdebug : IDE-level debugging experience, it is very convenient to watch variables by hovering over the mouse and execute them line by line
• Laravel's Telescope / Symfony's Profiler : If you are using frameworks, their own debugging tools are also very practical

The basic steps to install Xdebug include:

• Install the extension (via pecl or package manager)
• Modify php.ini to load xdebug and set remote connection parameters
• Configure the IDE listening debug port

Although the initial configuration is a bit troublesome, once it is installed, it will be much faster to check the problem.

Basically that's it. The key to debugging is not to guess, but to verify your assumptions step by step. As long as you master the above methods, most PHP problems can be solved.

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