Online PHP editor | refs for aqU8h

<?php /** * Get luhn checksum * * @param $str_string * @param $int_base * @return string */ function get_luhn_checksum($str_string, $int_base) { $arr_chars = array_reverse(str_split($str_string)); $int_check_sum = 0; foreach ($arr_chars AS $int_index=>$str_char) { $int_adjustment = ((int)base_convert($str_char, $int_base, 10)) * ($int_index % 2 ? 1 : 2); $int_check_sum += $int_adjustment; echo "char $int_index is $str_char adjustment is +$int_adjustment running checksum is $int_check_sum\n"; } echo "Final checksum is $int_check_sum modded = " . ($int_check_sum % $int_base) . "\n"; return strtoupper(base_convert($int_base - ($int_check_sum % $int_base), 10, $int_base)); } echo get_luhn_checksum('7992739871', 10); exit; $str = get_luhn_checksum('0B022412500000009104', 16); echo $str;