<?php
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 = "簡明現(xiàn)代魔法 —— 專注于互聯(lián)網(wǎng)主流的各種技術"; 
$length = "27"; 
$append = true; 
echo sysSubStr($string,$length,$append); 
// 輸出 
// 簡明現(xiàn)代魔法 —— 專...
?>

截取GB2312中文字符串：

復制代碼代碼如下:

<?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;
}
?>

截取utf8編碼的多字節(jié)字符串：

復制代碼代碼如下:

<?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);
}
?>

UTF-8、GB2312都支持的漢字截取函數(shù)：

復制代碼代碼如下:

<?php
/* 
Utf-8、gb2312都支持的漢字截取函數(shù) 
cut_str(字符串, 截取長度, 開始長度, 編碼); 
編碼默認為 utf-8 
開始長度默認為 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'); 
?>