How to use Xdebug for PHP function debugging?

By installing the Xdebug PHP extension and enabling it, you can debug PHP functions using an Xdebug client such as PhpStorm or VSCode. Set breakpoints, run scripts using the IDE, enter debug mode to inspect variables, perform step-by-step debugging, and view call stacks. In a practical use case, you can set a breakpoint on the sum function and use the debugger to view the variables and execution flow to debug errors or optimize the code.

How to use Xdebug for PHP function debugging

Introduction

Xdebug is a PHP extension for debugging PHP scripts. It provides rich functionality, including function tracing, variable inspection, and code coverage reporting. This tutorial will introduce how to install and use Xdebug for PHP function debugging.

Install Xdebug

To install Xdebug, please follow the steps below:

1. Go to the Xdebug official website to download the version that applies to your PHP version Xdebug installation package.
2. Unzip the installation package and copy the xdebug.so file to the PHP extension directory, usually located at /usr/local/lib/php/extensions/.

Enable Xdebug

To enable Xdebug, add the following line to your php.ini file:

zend_extension=/usr/local/lib/php/extensions/xdebug.so
xdebug.remote_enable=1
xdebug.remote_autostart=1

Debugging with Xdebug

1. Open the Xdebug client:Install an Xdebug client, such as PhpStorm or the Debugger extension for VSCode.
2. Set a breakpoint: Set a breakpoint in the function that needs to be debugged.
3. Run the script: Use an IDE with the Xdebug client to run the script.
4. Enter debug mode: After a script hits a breakpoint, the debugger will enter debug mode, allowing you to inspect variables, perform step-by-step debugging, and view the call stack.

Practical case

The following is how to use Xdebug to debug a simple PHP function:

function sum($a, $b) {
  return $a + $b;
}

$result = sum(1, 2);
echo $result;

1. atsum Set a breakpoint in the function.
2. Use an IDE with the Xdebug client to run the script.
3. When the script hits a breakpoint, the debugger will enter debug mode.
4. You can check the values ​​of variables $a and $b in the debugger and step through the function to see the execution flow.

Tip

• Use the xdebug_dump_function(...) function to dump the function call stack to a file. for a deeper analysis.
• Adjust the xdebug.max_nesting_level configuration setting to increase the maximum depth of nested functions that can be called recursively.

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