Check configuration file changes: Practical method of array_diff_assoc()

M66 2025-06-06

During development, we often need to check the differences between the two configuration files, especially when version updates or configuration files change. PHP provides the array_diff_assoc() function, which helps us efficiently compare two arrays and find elements that have differences in key names and values. In this article, we will parse the array_diff_assoc() function in detail and show how to use it to check the variations of configuration files.

1. Introduction to array_diff_assoc() function

array_diff_assoc() is a function in PHP used to compare two arrays. It returns an array containing all key names and values that exist in the first array but do not exist in the second array. Unlike array_diff() , array_diff_assoc() not only compares the values of an array, but also considers the key name.

grammar:

 array_diff_assoc(array $array1, array $array2): array

$array1 : The first array, the benchmark array for comparison.
$array2 : The second array, the target array to be compared.

Return value:

Returns an array containing elements that exist in $array1 but are missing in $array2 , and the key names and values of the elements are compared.

2. Use array_diff_assoc() to compare configuration files

We can use array_diff_assoc() to check for changes in configuration files, especially when updating configuration files, helping us identify new configuration items or deleted configuration items.

Suppose there are two configuration files:

Configuration file 1 ( config_v1.php )

 <?php
return [
    'site_url' => 'http://oldsite.m66.net',
    'site_name' => 'My Old Website',
    'theme' => 'default',
];

Configuration file 2 ( config_v2.php )

 <?php
return [
    'site_url' => 'http://newsite.m66.net',
    'site_name' => 'My New Website',
    'theme' => 'dark',
    'new_feature' => true,
];

We want to find out the differences in config_v1.php and config_v2.php , especially new or changed items.

Sample code:

 <?php
// Introduce two configuration files
$config1 = include('config_v1.php');
$config2 = include('config_v2.php');

// use array_diff_assoc() Comparison of the differences between two configuration files
$differences = array_diff_assoc($config2, $config1);

// Output variation difference
echo "Disparity of configuration file changes：\n";
print_r($differences);
?>

Analysis:

We first introduce two configuration files $config1 and $config2 through include() .
Then, we compare two configuration arrays using array_diff_assoc($config2, $config1) to find key-value pairs that are in $config2 but not in $config1 .
Finally, the difference is output via print_r() .

Running results:

 Disparity of configuration file changes：
Array
(
    [site_url] => http://newsite.m66.net
    [site_name] => My New Website
    [new_feature] => 1
)

As you can see, the output contains configuration items that are newly added or changed in the second configuration file. Pay special attention to the changes in the values of the two configuration items site_url and site_name . new_feature is a newly added configuration item.

3. Practical application scenarios

In practical applications, array_diff_assoc() is very suitable for the following scenarios:

Profile comparison : When you release a new version, you can use it to compare new and old configuration files to quickly identify newly added or deleted configuration items.
Database migration : If you have any changes in the database structure, you can compare the changes in the database configuration file in this way to find out the data that needs to be migrated.
Version control : You can use array_diff_assoc() to detect configuration differences between different versions, helping the development team to quickly locate the changing parts.

4. Summary

Through this article, we understand the basic usage of the array_diff_assoc() function and how to use it to check the variations of configuration files. This function has great application value in scenarios such as version control, configuration management, and database migration. Mastering its use can help us manage configuration file differences in projects more efficiently.

If you have other questions about PHP functions, feel free to ask them. Let us explore more PHP tips together!

array_diff_assoc