How do active class on pagination

I’m trying to active class on list

Kindly if any one can help me to add class="active" on displayed pagination page:

$perpage= $conf['perpage'];
if (isset($_GET["page"])) { 
    $page  = $_GET["page"]; 
} else { 
    $page=1; 
}; 
$start_from = ($page-1) * $perpage; 
$result = "SELECT * FROM topics LIMIT $start_from, $perpage"; 
$result = mysql_query ($result); 
$n = 0;
while ($row = mysql_fetch_array ($result)){
    echo '<tr>';
    echo '<td>'.$row['topic_no'].'</td>';
    echo '</tr>';
    ++$n;
}


$sql = "SELECT * FROM topics"; 
$result = mysql_query($sql); 
$total_records = mysql_num_rows($result);  
$total_pages = ceil($total_records / $perpage); 
echo '<ul class="pagination">'; 
echo "<li><a href='topics.php?page=1'>".'<'."</a></li> ";  

for ($i=1; $i<=$total_pages; $i++) { 
    echo "<li  ><a href='topics.php?page=".$i."'>".$i."</a></li> "; 
}; 
echo "<li><a href='topics.php?page=$total_pages'>".'>'."</a> </li>"; 

echo '</ul> ';

Thanks in Advance

Answer

  echo "<li if($_GET['page']==$i){ class='active'}><a href='topics.php?page=".$i."'>".$i."</a></li> ";

Please try this. It might help you