PHP mysqli_field_tell() Function

<?php
$con=mysqli_connect("localhost","my_user","my_password","my_db");
// Check connection
if (mysqli_connect_errno())
  {
  echo "Failed to connect to MySQL: " . mysqli_connect_error();
  }

$sql="SELECT Lastname,Age FROM Persons ORDER BY Lastname";

if ($result=mysqli_query($con,$sql))
  {

  // Get field info for all fields
  while ($fieldinfo=mysqli_fetch_field($result))
    {
    // Get field cursor position
    $currentfield=mysqli_field_tell($result);
   
    printf("Column %d:\n", $currentfield);
    printf("Name: %s\n", $fieldinfo->name);
    printf("Table: %s\n", $fieldinfo->table);
    }

  // Free result set
  mysqli_free_result($result);
  }

mysqli_close($con);
?>