php 截取中文字符串实现程序

//$str是要截取的字符串
//$start是要截取的字符的开始位置
//$len是指要截取的字符长度
function sub_str($str, $start, $len) {
        $tmpstr = "";
        $strlen = $start + $len;
        for($i = 0; $i             if(ord(substr($str, $i, 1)) > 0xa0) {
                $tmpstr .= substr($str, $i, 2);
                $i++;
            } else
                $tmpstr .= substr($str, $i, 1);
        }
        return $tmpstr."...";
}

//截取utf8字符串
function utf8substr($str, $from, $len)
{
    return preg_replace('#^(?:[x00-x7f]|[xc0-xff][x80-xbf]+){0,'.$from.'}'.
                       '((?:[x00-x7f]|[xc0-xff][x80-xbf]+){0,'.$len.'}).*#s',
                       '$1',$str);
}
?>

/**
 * @package     BugFree
 * @version     $Id: FunctionsMain.inc.php,v 1.32 2005/09/24 11:38:37 wwccss Exp $
 *
 *
 * Return part of a string(Enhance the function substr())
 *
 * @author                  Chunsheng Wang
 * @param string  $String  the string to cut.
 * @param int     $Length  the length of returned string.
 * @param booble  $Append  whether append "...": false|true
 * @return string           the cutted string.
 */
function sysSubStr($String,$Length,$Append = false)
{
    if (strlen($String)     {
        return $String;
    }
    else
    {
        $I = 0;
        while ($I         {
            $StringTMP = substr($String,$I,1);
            if ( ord($StringTMP) >=224 )
            {
                $StringTMP = substr($String,$I,3);
                $I = $I + 3;
            }
            elseif( ord($StringTMP) >=192 )
            {
                $StringTMP = substr($String,$I,2);
                $I = $I + 2;
            }
            else
            {
                $I = $I + 1;
            }
            $StringLast[] = $StringTMP;
        }
        $StringLast = implode("",$StringLast);
        if($Append)
        {
            $StringLast .= "...";
        }
        return $StringLast;
    }
}

$String = "www.111cn.net 走在中国自动化测试的前沿";
$Length = "18";
$Append = false;
echo sysSubStr($String,$Length,$Append);
?>