From entry to proficiency, a complete guide to PHP debugging

PHP debugging methods include: using var_dump() and print_r() to view variable contents. Enable Xdebug for advanced debugging. Use logging to capture events. Take advantage of the debugging capabilities provided by your IDE.

From beginner to proficient: A complete guide to PHP debugging

Introduction

Debugging is a crucial part of software development. It has Helps locate and fix problems in the code. In PHP, there are several powerful and practical methods that can help you debug your application efficiently.

Using var_dump and print_r

The var_dump() and print_r() functions are convenient tools for viewing the contents of variables. var_dump() displays the details of a variable, including type, value, and structure, while print_r() displays the variable in a more readable format.

$arr = [1, 2, 3];

var_dump($arr); // 输出：array(3) { [0] => int(1) [1] => int(2) [2] => int(3) }
print_r($arr); // 输出：Array ( [0] => 1 [1] => 2 [2] => 3 )

Enable Xdebug

Xdebug is a popular PHP debugger that provides a rich set of features, including execution tracing, variable inspection, and code coverage. To enable Xdebug, add the following configuration to your php.ini file:

[xdebug]
zend_extension = /path/to/xdebug.so
xdebug.remote_enable = 1

Then connect to the Xdebug debugger via the following code in your script:

// 启动调试会话
xdebug_start_debug();

Use Logging

Logging is an effective way to capture events that occur while a program is running. You can use this information to debug unexpected behavior and perform diagnostics:

error_log("An error occurred: " . $error_message);

Using an IDE

IDEs such as PHPStorm and Visual Studio Code provide built-in debugging capabilities to make debugging more convenient. These tools use features such as breakpoints, stack traces, and variable inspection to help you locate problems.

Practical Case

Suppose you have a PHP script that calculates the sum of two numbers:

<?php
function add($num1, $num2) {
  return $num1 + $num2;
}

$result = add(5, 10);
echo $result; // 输出：15

Now, you find that the script cannot calculate the sum correctly. You can use the var_dump() function to debug this problem:

<?php
function add($num1, $num2) {
  var_dump($num1); // 输出：int(5)
  var_dump($num2); // 输出：int(10)
  return $num1 + $num2;
}

$result = add(5, 10);
echo $result; // 输出：15

By inspecting the variable contents, you will see that the number passed to the add() function is correct, so the problem lies elsewhere.

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