set html dropdown to selected value after refresh

how do i set a dropdown menu to a get variable after refresh. there is an html menu and after a refresh i would like the dropdown to be set to the select variable. for example if i select 3 from the menu then click submit the dropdown should display 3. i used to do this with textboxes where i would set the value to the get variable im just trying to do this same technique with html dropdown menus.

</select>
                <?php
                $c=$_GET['c'];
         开发者_开发知识库       $p=$_GET['p'];
                $id=$_GET['id'];



                if ($c!=NULL){


                        $sq=mysql_query("SELECT * FROM ps WHERE b='$id' AND c='$c'"); 


                            while ($row=mysql_fetch_assoc($sq)) { 


                            $start=$row['start'];
                            $start=trim($start);
                            $m=$row['m'];


                            }

                        echo "<select type='text' name='pro' id='amount' value= '$p'>";
                            echo "<option value=''>P</option>";
                                while ($start<=$m){

                                echo "<option value='$start'>$start</option>";

                                $start++;

                                }



                }
    ?>
                    </select>

Is this in a form? If so you echo options like this:

   echo "<option value='$start'";
   if (isset($_POST['pro']) && ($_POST['pro']==$start)) echo " selected='selected'";
   echo ">$start</option>\n";

But first you need to submit the form though. The idea is that you compare the value of a set variable for this select element to current value of $start within the loop, and print 'selected' if they match.

Is this what you meant??

http://www.plus2net.com/php_tutorial/pb-drop.php