php printf 的问题
想把number   of   record   的内容print出来，可是在页面上无法显示，无错误提示信息。
      $link   =   new   mysqli( 'localhost ', 'root ', ' ', 'book ');
if(mysqli_connect_errno())
      {
          echo   '   connection   failed '.mysqli_connect_error();
      }
$query   =   insert   into   detail   values        
( ' .$title. ', ' .$author. ', ' .$isbn. ', ' .$price. ') ;
      $result   =   $link-> query($query);
      $num   =   $link-> affected_rows;
if   ($result)
      {
        //   echo   $num.   'record   inserted   into   database ';
        //就是这一行想显示出来，可是无法在页面上显示//
        printf( %c   record   stored   in   the   database ,$num);
      }
$link-> close();
}
请教到底怎么回事？谢谢
------解决方案--------------------
c - the argument is treated as an integer, and presented as the character with that ascii value.
d - the argument is treated as an integer, and presented as a (signed) decimal number.
printf( %d record stored in the database ,$num);