Question

Given that when using an html radio box, to send values to a php script, only the selected values is sent to the php script, still holds true.

Do I still need to check that the user has selected something, when I am only interested in the selected value being sent to the php script, if the user does not select anything we do nothing or I guess I could prompt the user to select something.

If so, whats the best way to handle this with regards to radio boxes?

 <!--Using the radio box, a single selected value is sent to the php script for processing-->
    <td width="100px" height="30px">  
    <input type = "radio"
    name = "selection"
    value = "Lays" />Lays Chips 0.99c<br />

    <input type = "radio"
    name = "selection"
    value = "Ruffles" />Ruffles $1.85<br />

Answer 1

The user will be able to click the “submit” button even without selecting an option from your radiobox.

If it’s ok to send the form without a selection and you just want to do something different (or ignore it) when nothing is selected, you can do this:

<?php
  if (isset(($_POST['selection'])) {
    //Use it.. and make sure to validate user input.
  } else {
    //nothing was selected. Do something or just ignore?
  }
?>

OTOH, if you want to prevent submiting without a selection, you will need to use some JavaScript to do it.