Find words in which letters are in alphabetical order

alphabetical_order_in_words.php

<?php
$str = "abcd 01234 87 01235 6 абвгд";
$words = preg_split("/\s/", $str, -1, PREG_SPLIT_NO_EMPTY);

function uniord($ch) {

    $n = ord($ch{0});

    if ($n < 128) {
        return $n; // no conversion required
    }

    if ($n < 192 || $n > 253) {
        return false; // bad first byte || out of range
    }

    $arr = array(1 => 192, // byte position => range from
                 2 => 224,
                 3 => 240,
                 4 => 248,
                 5 => 252,
                 );

    foreach ($arr as $key => $val) {
        if ($n >= $val) { // add byte to the 'char' array
            $char[] = ord($ch{$key}) - 128;
            $range  = $val;
        } else {
            break; // save some e-trees
        }
    }

    $retval = ($n - $range) * pow(64, sizeof($char));

    foreach ($char as $key => $val) {
        $pow = sizeof($char) - ($key + 1); // invert key
        $retval += $val * pow(64, $pow);   // dark magic
    }

    return $retval;
}

$found_words = array();

if(count($words) > 0) {
	foreach($words as $word) {
		$flag = false;
		if(mb_strlen($word) == 1) {
			$found_words[] = $word;
			continue;
		}
		$chars = preg_split("//u", $word, -1, PREG_SPLIT_NO_EMPTY);

		for($i = 1; $i < count($chars); $i++) {
			if(uniord($chars[$i]) == (uniord($chars[$i-1]) +1)) {
				$flag = true;
			} else {
				$flag = false;
				break;
			}
		}
		if(true === $flag) {
			$found_words[] = $word;
		}
	}
}
var_dump($found_words);