- array_column: documentation ( source)
- var_export: documentation ( source)
- array_values: documentation ( source)
<?php
$array = [
['user_id' => 82, 'ac_type' => 1],
['user_id' => 80, 'ac_type' => 5],
['user_id' => 76, 'ac_type' => 1],
['user_id' => 82, 'ac_type' => 2],
['user_id' => 80, 'ac_type' => 5]
];
var_export(array_values(array_column($array, null, 'user_id')));