PHP截取字符串[GB2312-UTF8编码]

1. 截取GB2312中文字符串
<?php
//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 $tmpstr;
}
?>
2. 截取utf8编码的多字节字符串
<?php
//截取utf8字符串
function utf8Substr($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);
}
?>
3. UTF-8、GB2312都支持的汉字截取函数
<?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 $tmpstr;
    }
}$str = "abcd需要截取的字符串";
echo cut_str($str, 8, 0, 'gb2312');
?>
4. BugFree 的字符截取函数
<?php
/**
* @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 $Append whether append "...": false|true
* @return string           the cutted string.
*/
function sysSubStr($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 $StringLast;
    }
}$String = "www.at0915.cn";
$Length = "18";
$Append = false;
echo sysSubStr($String,$Length,$Append);
?>