How to use PHP's Xdebug extension?

PHP’s Xdebug extension is a very powerful debugging tool, especially useful for PHP developers. This article will introduce how to use the Xdebug extension for debugging in PHP.

Xdebug is an extension that can assist PHP developers in debugging. It provides many useful features such as tracking function calls, logging variables and execution times, etc. Using Xdebug can make it easier for PHP developers to find and correct problems in the code and improve development efficiency.

Install Xdebug extension

To use Xdebug, you first need to install it into PHP. You can install it by running the following command in the terminal:

pecl install xdebug

After the installation is complete, you can use the phpinfo() function to check whether the Xdebug extension has been successfully installed. If you see output similar to the following, it means that it has been successfully installed:

Xdebug support

Enable Xdebug debugging

After installing Xdebug, you need to enable it in PHP Debugging capabilities. Debugging can be turned on by configuring it in the php.ini file. Add the following content to the php.ini file:

[xdebug]
xdebug.remote_enable=1
xdebug.remote_autostart=1

This will enable Xdebug’s remote debugging functionality. In order for PHP to correctly connect to the debugger, you also need to set xdebug.remote_host to the IP address of the debugger.

Configuring the debugger

After installing Xdebug and turning on the debugging function, you need a debugger to communicate with PHP. The following are the steps on how to configure the debugger:

1. Download the Xdebug debugger tool (such as the commonly used PHPStorm or Visual Studio Code) and install it.
2. Open the debugger's settings interface and configure the debugger's listening port number. Usually, the default port number of Xdebug is 9000.
3. Open the debug mode of the project in the debugger and set breakpoints. At this point, the debugger will be waiting on the listening port for PHP to send a debugging request.

Debug

After the above steps are completed, you can use Xdebug for debugging. Use the following steps to enter debug mode:

1. Load the Xdebug extension in PHP.

2. Enable debug mode:

   • When running PHP on a web server, add "?XDEBUG_SESSION_START=" to the end of the URL.
   • When running PHP in command line mode, use the -xdebug parameter to start the script.
3. PHP will establish a connection with the debugger and stop when a breakpoint is encountered.
4. In the debugger, you can view variables, view the call stack, single-step through the code, etc.

Summary

Using Xdebug can make PHP development more efficient and faster. This article describes how to install and configure Xdebug, and use the debugger for debugging. These steps make it easier for PHP developers to find and solve problems in their code.

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