Check Japanese Characters string

count_string_length_japanese.php

<?php
class JapaneseCharacters {
	/**
	 * Check character is half-width Katakana
	 *
	 * @param string $char
	 * @return boolean
	 */
	public static function checkKatakana($char) {
		return (preg_match('/[\x{FF61}-\x{FF9F}]/u', $char) > 0);
	}

	/**
	 * Count lent string utf8 full=1, half=0.5
	 * @param string $str
	 * @return float
	 */
	public static function strlen_utf8($str = '') {
		if ($str === "") {
			return 0;
		}

		$count = 0;
		$str = str_replace('&#34;', '"', $str);
		$str = str_replace('&#39;', "'", $str);
		$str = str_replace("\r", '', $str);
		$str = html_entity_decode($str);
		$w_list = preg_split('//u', $str, -1, PREG_SPLIT_NO_EMPTY);
		for ($i = 0; $i < count($w_list); $i++) {
			if ((strlen($w_list[$i]) > 1 || ($w_list[$i] == "\n")) && !self::checkKatakana($w_list[$i])) {
				$count += 1;
			} else {
				$count += 0.5;
			}
		}
		return $count;
	}

}