php怎样限制字符的显示长度？

Question

像上面这样(截取贴吧的)，当字符长度超过固定的像素宽度时，截取像素宽度范围内的字符串，并在字符串后加省略号。mb_strlen函数只能获取字符数，而英文和中文一个字符所占的宽度不一样，不能根据字符数来确定，不知道该怎么实现？

Answer 1

那个可以通过 CSS 来控制的… http://jsfiddle.net/sc7uk5bw/

Answer 2

//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;
    }else{
        return $slice;
    }

}

Answer 3

给一个我平时用来截取字符串的方法吧，支持中英文

php// 截取字符串
public static function mix_substr($str, $len = 12, $dot = true) {
    $i = 0;
    $l = 0;
    $c = 0;
    $a = array();
    while ($l < $len) {
        $t = substr($str, $i, 1);
        if (ord($t) >= 224) {
            $c = 3;
            $t = substr($str, $i, $c);
            $l += 2;
        } elseif (ord($t) >= 192) {
            $c = 2;
            $t = substr($str, $i, $c);
            $l += 2;
        } else {
            $c = 1;
            $l++;
        }
        // $t = substr($str, $i, $c);
        $i += $c;
        if ($l > $len) break;
        $a[] = $t;
    }
    $re = implode('', $a);
    if (substr($str, $i, 1) !== false) {
        array_pop($a);
        ($c == 1) and array_pop($a);
        $re = implode('', $a);
        $dot and $re .= '...';
    }
    return $re;
}