How to debug php

The following examples are all based on the LNMP environment under Windows.

Debug by printing information from the browser (Recommended learning: PHP video tutorial)

Method

Add echo, var_dump, print_r and exit to the code and view the output in the browser.

Advantages and Disadvantages

Advantages:

Simple, easy to use, no need to install plug-ins

For self-written code, or more familiar frameworks, you can do this Using

Disadvantages:

For multi-branch logic, you need to add a lot of code or try multiple times

For unfamiliar logic, the complete execution process cannot be reflected.

It is possible to leave debugging statements in the project

Unable to single step

Use Xdebug for debugging

XDebug is C /S structure, where Client is Xdebug installed in PHP, Server is the plug-in installed in IDE, and uses DBGP protocol to communicate. When PHP runs a script, it sends debugging information to the IDE through the Xdebug plug-in and receives control signals from the IDE.

You need to install and enable Xdebug for PHP, and then set up the IDE's Xdebug plug-in so that the two can communicate.

Advantages and Disadvantages

Supports single-step debugging and acquisition of arbitrary variable values

The configuration is complicated and requires IDE to install plug-ins

Supports cooperation with browsers, The request needs to carry the XDEBUG_SESSION_START parameter

Web App Debugging

For web applications, to enable the Xdebug debugging mode, additional flags must be added to the request sent by the browser. You can add XDEBUG_SESSION_START=session_name in the GET/POST/Cookie parameters, so that Xdebug will understand that this request needs to be debugged and connect to the IDE.

Debug through the console terminal (CLI mode)

For non-web applications, such as scheduled tasks or unit tests, you can debug directly on the console.

Open the command line terminal in PhpStorm through the Alt F12 shortcut key. However, because only one terminal can be displayed in the IDE, the debugging terminal after debugging is turned on will cover the command line terminal, so it is better to open a separate command line terminal (you can use a DOS window or PowerShell under Windows).

Method and Principle

Web applications mark debugging requests through GET/POST/Cookie parameters, while non-web applications enable debugging by setting environment variables in the command line terminal.

Two steps:

Set the environment variable XDEBUG_CONFIG="idekey=session_name". This idekey needs to be the same as the idekey set in the Xdebug section of php.ini.

Execute the script in the command line terminal. When executed, the debug terminal of the IDE will be evoked, allowing single-step debugging, and the output results will be displayed in the command line terminal in real time.

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