Way to get all alphabetic chars in an array in PHP?

$alphas = range('A', 'Z');

Documentation: https://www.php.net/manual/en/function.range.php

To get both upper and lower case merge the two ranges:

$alphas = array_merge(range('A', 'Z'), range('a', 'z'));

$alphabet = array('A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z');