php calculate string length

In the development of the project, it is often encountered to calculate the length of a string (combination of Chinese and English). Due to different product requirements, the length requirements of each Chinese are also different.

Solve the string length under utf-8 encoding (you can customize how many bytes each Chinese and English count)

/**
 * Calculate the string length
 * @author Timothy
 * @param null $string The string to be calculated, default null
 * @param int $chinese How many bytes Chinese occupies, default 2
 * @param int $other Other characters count as several bytes, default 1
 * @return int length returned
 */
private function utf8_strlen($string = null, $chinese = 2, $other = 1) {
    // break the string into units
    preg_match_all("/./us", $string, $match);
    $pattern = '/[^\x00-\x80]/';
    $count = 0;
    foreach ($match[0] as $key => $value) {
        $count = preg_match($pattern, $value) ? ($count + $chinese) : ($count + $other);
    }

    return $count;
}
Note:
1. preg_match_all("/./us", $string, $match);//"/./us", u means the default utf-8 encoding, s  (PCRE_DOTALL) means
If this modifier is set, the dot metacharacter (.) in the pattern matches all characters, including newlines. Without this setting, newlines are not included.
2. $pattern = '/[^\x00-\x80]/';//means matching Chinese