php常用方法—字符串截取

//截取中文字符串
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));
    return $suffix ? $slice.'...' : $slice;
}

第二种：

/**
 * 字符串截取
 * @param $string
 * @param string $length
 * @param string $charset
 * @return NULL|string
 */
function truncate($string, $length = '100',$charset='utf-8') {
	$string= trim(strip_tags(htmlspecialchars_decode($string)));
	$string=str_replace(array(' ','&nbsp;',"\t","\n","<br/>"), array('','','','',''), $string);
	$len = mb_strlen($string,$charset);
	if($len == 0){
		//return '暂无简介数据...';
		return NULL;
	}else if($len < $length && $len > 0){
		return $string.'...';
	}else{
		return mb_substr($string, 0,$length,$charset).'...';
	}
}