Converts string to title case

TitleCase.php

<?php declare(strict_types=1);

if (!function_exists('titleCase')) {

    function titleCase($title)
    {
        $smallWords = [
            'a',
            'an',
            'and',
            'at',
            'but',
            'by',
            'else',
            'for',
            'from',
            'if',
            'in',
            'into',
            'is',
            'nor',
            'of',
            'off',
            'on',
            'or',
            'out',
            'over',
            'the',
            'then',
            'to',
            'when',
            'with'
        ];

        $specialWords = [
            'I',
            'II',
            'III',
            'IV',
            'V',
            'VI',
            'VII',
            'UK',
            'US'
        ];

        $punctuation = [
            '.',
            '-',
            ':',
            '!',
            '?'
        ];

        $words = explode(' ', $title);

        foreach ($words as $index => $word) {
            $lastCharacterPreviousWord = substr($index -1, -1);

            if (
                !in_array($word, $smallWords) ||
                !in_array($word, $specialWords) ||
                in_array($lastCharacterPreviousWord, $punctuation) ||
                $index === 0
            ) {
                $words[$index] = ucfirst($word);
            }
        }

        $title = implode(' ', $words);

        return $title;
    }
}