how array_filter works in php code example

Example 1: php array filter

<?php

$arr = ['a' => 1, 'b' => 2, 'c' => 3, 'd' => 4];

var_dump(array_filter($arr, function($k) {
    return $k == 'b';
}, ARRAY_FILTER_USE_KEY));

var_dump(array_filter($arr, function($v, $k) {
    return $k == 'b' || $v == 4;
}, ARRAY_FILTER_USE_BOTH));
?>

Example 2: php filter array

$numbers = [-2, 4, -6, 8, 10];

function isPositive($number)
{
  return $number > 0;
}

$filteredArray = array_filter($numbers, "isPositive");