array_filter and strlen to filter array

gistfile1.txt

<?php
        $array = array(
                0,
                '',
                false,
                1,
                '0'
        );
        print_r( $array );
        print_r( array_filter( $array, 'strlen' ) );
?>

Produce: 
Array
(
    [0] => 0
    [1] => 
    [2] => 
    [3] => 1
    [4] => 0
)
Array
(
    [0] => 0
    [3] => 1
    [4] => 0
)

As of PHP 8.1, strlen will now emit a deprecated error "strlen(): Passing null to parameter #1 ($string) of type string is deprecated"