中英文字符串截取类

<?php

/**
 * description：中英文字符串截取 
 * @author ：SunsCheung
 * @date：2015-09-24
 */
class Helper{
    public static function truncate_utf8_string($string, $length, $etc = ‘...‘)
    {
        $result = ‘‘;
        $string = html_entity_decode(trim(strip_tags($string)), ENT_QUOTES, ‘UTF-8‘);
        $strlen = strlen($string);
        for ($i = 0; (($i < $strlen) && ($length > 0)); $i++)
        {
            if ($number = strpos(str_pad(decbin(ord(substr($string, $i, 1))), 8, ‘0‘, STR_PAD_LEFT), ‘0‘))
            {
                if ($length < 1.0)
                {
                    break;
                }
                $result .= substr($string, $i, $number);
                $length -= 1.0;
                $i += $number - 1;
            }
            else
            {
                $result .= substr($string, $i, 1);
                $length -= 0.5;
            }
        }
        $result = htmlspecialchars($result, ENT_QUOTES, ‘UTF-8‘);
        if ($i < $strlen)
        {
            $result .= $etc;
        }
        return $result;
    }
}