通用的截取字符串函数(php)

/*
Utf-8、gb2312都支持的汉字截取函数
cut_str(字符串, 截取长度, 开始长度, 编码);
编码默认为 utf-8
开始长度默认为 0
*/
function cut_str($string, $sublen, $start = 0, $code = ‘UTF-8’)
{
    if($code == ‘UTF-8’)

    {

       $pa ="/[\x01-\x7f]|[\xc2-\xdf][\x80-\xbf]|\xe0[\xa0-\xbf][\x80-\xbf]|[\xe1-\xef][\x80-\xbf][\x80-\xbf]|\xf0[\x90-\xbf][\x80-\xbf][\x80-\xbf]|[\xf1-\xf7][\x80-\xbf][\x80-\xbf][\x80-\xbf]/";

        preg_match_all($pa, $string, $t_string);

  if(count($t_string[0]) – $start > $sublen)

   return join('', array_slice($t_string[0], $start, $sublen))."...";

        return join('', array_slice($t_string[0], $start, $sublen));

    }

    else

    {

        $start = $start*2;

        $sublen = $sublen*2;

        $strlen = strlen($string);

        $tmpstr = '';        for($i=0; $i<$strlen; $i++)

        {

            if($i>=$start && $i<($start+$sublen))
            {
                if(ord(substr($string, $i, 1))>129)

                {

                    $tmpstr.= substr($string, $i, 2);

                }

                else

                {

                    $tmpstr.= substr($string, $i, 1);

                }

            }

            if(ord(substr($string, $i, 1))>129) $i++;

        }

        if(strlen($tmpstr)<$strlen ) $tmpstr.= "...";

        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).'...';

}


//截取中文字符串

function mysubstr($str, $start, $len) {

    $tmpstr = "";

    $strlen = $start + $len;

    for($i = 0; $i < $strlen; $i++) {

        if(ord(substr($str, $i, 1)) > 0xa0) {

            $tmpstr .= substr($str, $i, 2);

            $i++;

        } else

            $tmpstr .= substr($str, $i, 1);

    }

    return $tmpstr;

}


/**
* @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 <[email]wwccss@263.net[/email]>
* @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.

* $String = "www.szsite.net";

* $Length = "18";

* $Append = false;

* echo sysSubStr($String,$Length,$Append);

*/
function sysSubStr($String,$Length,$Append = false)
{
    if (strlen($String) <= $Length )

    {

        return $String;

    }

    else

    {

        $I = 0;

        while ($I < $Length)

        {

            $StringTMP = substr($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;

    }

}