How do I create a user defined function for mysqli_num_rows in php OOPs? -

i have tried best find out result on own, have failed.

here's source code have tried @ level best.

<?php  class database {     private $connect;     private $dbuser;     private $dbhost;     private $dbpassword;     private $dbdatabase;     private $numrows;     private $results;      public function connect($host, $username, $pass, $db)     {         $this->dbhost = $host;         $this->dbuser = $username;         $this->dbpassword = $pass;         $this->dbdatabase = $db;          return $this->connect = mysqli_connect($this->dbhost, $this->dbuser, $this->dbpassword, $this->dbdatabase);     }      public function disconnect($connect) {         return mysqli_close($this->connect = $connect);     }      public function select($table, $where = array(), $orderby = null) {         if (count($where) === 3) {             $operators = array('=', '<', '>', '>=', '<=', 'like');              $field = $where[0];             $operator = $where[1];             $value = $where[2];              if (in_array($operator, $operators)) {                 $query = "select * {$table} '". $field . $operator . $value . "'";             }              if (mysqli_query($this->connect, $query)) {                 return true;             } else {                 die(mysqli_error($this->connect));             }         }     }      public function countrows($queryres)     {         if (mysqli_num_rows($queryres) > 0) {             return true;         } else {             return false;         }     } } 

i error:

warning: mysqli_num_rows() expects parameter 1 mysqli_result, boolean given in c:\wamp\www\practice\index.php on line 70

and line 70 is: if (mysqli_num_rows($queryres) > 0) {

here's , how call method:

$suc = ""; if (isset($_post['btnsubmit'])) {     $con = new database();     $objdb = $con->connect('localhost', 'root', '', 'practice');      $username = $_post["username"];      $suc = $con->select('users', ['username', 'like', '%'.$username.'%']);      if ($suc) {         print_r($con->countrows($suc));     } else {         echo "unable find record !";     }     //print_r($suc);      $con->disconnect($objdb); } ?> 

kindly guide me making mistake.

thanks

function countrows($sql) {    $rst              =  @mysql_query($sql)or trigger_error("sqxxxl", e_user_error);    return $numrows       =  mysql_num_rows($rst); }