👀 Views: 63 💬 Answers: 1 📅 Created: 2025-07-22

php usort arrays sorting PHP

I'm working with a perplexing scenario when using `usort` in PHP 8.1 with a custom comparison function. I have an array of associative arrays representing user data, and I want to sort them based on a 'score' key. The comparison function seems to return inconsistent results, leading to unexpected orderings in the sorted array. Here’s the code snippet of what I’ve tried: ```php $users = [ ['name' => 'Alice', 'score' => 85], ['name' => 'Bob', 'score' => 90], ['name' => 'Charlie', 'score' => 85], ]; usort($users, function ($a, $b) { if ($a['score'] === $b['score']) { return 0; } return ($a['score'] < $b['score']) ? 1 : -1; }); ``` I expect the output to be sorted with Bob first, followed by Alice and Charlie in any order since they have the same score. However, the results seem to vary on different runs, and sometimes Charlie appears before Alice. I have verified that the 'score' values are indeed integers. I also tried logging the values in the comparison function, but they seem to reflect the correct values on every invocation, yet the final order in the `$users` array is not consistent. Is there something I am missing regarding the comparison logic or usage of `usort`? Any insights into how `usort` handles ties or best practices to ensure consistent ordering would be greatly appreciated!