分享两个截取字符串已封装好的函数

// 截取字符串函数

function subtext($text, $length)

{
    if(mb_strlen($text, 'utf8') > $length)
        return mb_substr($text, 0, $length, 'utf8').'...';
    return $text;
}

//函数解释：  
//msubstr($str, $start=0, $length, $charset=”utf-8″, $suffix=true)  
//$str:要截取的字符串  
// $start=0：开始位置，默认从0开始  
// $length：截取长度  
// $charset=”utf-8″：字符编码，默认UTF－8  
// $suffix=true：是否在截取后的字符后面显示省略号，默认true显示，false为不显示  
//模版使用：{$vo.title|msubstr=0,5,'utf-8',false}  
//把如下代码粘贴到thinkphp核心包的/common/functions.php 的最后便可在html模型里直接使用  
  
//截取字符串  
function msubstr($str, $start=0, $length, $charset="utf-8", $suffix=true)    
{    
    if(function_exists("mb_substr"))  
    {    
        if($suffix)    
            return mb_substr($str, $start, $length, $charset)."...";    
        else  
            return mb_substr($str, $start, $length, $charset);    
    }    
    elseif(function_exists('iconv_substr'))   
    {    
        if($suffix)    
            return iconv_substr($str,$start,$length,$charset)."...";    
        else  
            return iconv_substr($str,$start,$length,$charset);    
    }    
    $re['utf-8']   = "/[x01-x7f]|[xc2-xdf][x80-xbf]|[xe0-xef]  
    [x80-xbf]{2}|[xf0-xff][x80-xbf]{3}/";    
    $re['gb2312'] = "/[x01-x7f]|[xb0-xf7][xa0-xfe]/";    
    $re['gbk']    = "/[x01-x7f]|[x81-xfe][x40-xfe]/";    
    $re['big5']   = "/[x01-x7f]|[x81-xfe]([x40-x7e]|xa1-xfe])/";    
    preg_match_all($re[$charset], $str, $match);    
    $slice = join("",array_slice($match[0], $start, $length));    
    if($suffix) return $slice."…";    
    return $slice;  
}