3v4l.org

run code in 300+ PHP versions simultaneously
<?php $string = 'abclkjabc'; echo count(array_filter(count_chars($string, 1), fn($count) => $count === 1));
Output for 7.4.0 - 7.4.33, 8.0.1 - 8.0.30, 8.1.0 - 8.1.31, 8.2.0 - 8.2.26, 8.3.0 - 8.3.14, 8.4.1
3
preferences:
59.72 ms | 406 KiB | 5 Q