php如何隱藏字串中部分字元

經常在公布中獎名單時，為了避免曝光中獎者的手機號碼，於是採用隱藏中間部分數字來呈現，比如：139****2972，本文簡單分享一段php實現的代碼，希望能協助到大家。

// 隱藏部分字串function func_substr_replace($str, $replacement = '*', $start = 1, $length = 3){    $len = mb_strlen($str,'utf-8');    if ($len > intval($start+$length)) {        $str1 = mb_substr($str,0,$start,'utf-8');        $str2 = mb_substr($str,intval($start+$length),NULL,'utf-8');    } else {        $str1 = mb_substr($str,0,1,'utf-8');        $str2 = mb_substr($str,$len-1,1,'utf-8');            $length = $len - 2;            }    $new_str = $str1;    for ($i = 0; $i < $length; $i++) {         $new_str .= $replacement;    }    $new_str .= $str2;    return $new_str;}