PHP forms which retain value on submit
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Ok so I got a form and usability is important to me. If the user completes the form and then hits submit but there are errors on the form I have set values to echo back

e.g. 
`<input class="input_phone" name="phone" type="text" value="<?php echo $_POST['phone']; ?>" maxlength="15" />`

The value entered will be back in the form field so that the user doesn't have to retype every field.

How do i achieve the same effect with radio buttons?

`<input class="radio" name="q1" type="radio" value="YES">`

If i set the value to `$_POST['q1']` How do I set it to `YES`?


