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ASP Source Code:
<h2>Some sample radio button form elements:</h2>
<form action="<%= Request.ServerVariables("URL") %>" method="get">
  A Default No-Frills Radio Button:
  <input type="radio" name="default" />
  <br />
  Radio Button With An Associated Value:
  <input type="radio" name="value_specified" value="Some Value" />
  <br />
  Multiple Radio Buttons With The Same Name:
  <input type="radio" name="multiple" value="1" />
  <input type="radio" name="multiple" value="2" />
  <input type="radio" name="multiple" value="3" />
  <br />
  Radio Button Which Maintains Its State:
  <input type="radio" name="state_keeper"
  <%
  ' This is the code that keeps the state of the radio
  ' button.  All it does is check to see if the value
  ' returned is the same as the value parameter of the
  ' radio button input tag.  If so, the radio button was
  ' enabled and we output the input tag's "checked"
  ' attribute to keep it that way.
  If Request.QueryString("state_keeper") = "on" Then
	Response.Write " checked=""checked"""
  End If
  %>
  />
  <br />
  <br />
  <input type="submit" />
</form>
<br />
<br />
<br />
<h2>Let's check out our values just submitted:</h2>
<blockquote><em>
FYI: Note that the above form submits back to this same page.
If you haven't yet submit the form then there won't be
any values in the text below since they are retrieved
from the form.  In this case, the values reflected are
simply the defaults and are the same results you would
get if you submitted the form without checking anything.
</em></blockquote>
<p><strong>The Default No-Frills Radio Button</strong></p>
<p>
By default, an HTML radio button element returns nothing
if it wasn't enabled and a value of "on" if it
was.  So by checking its value we can determine if it was
enabled or not when the form was submitted.
The No-Frills Radio Button was: <strong>
<%
' Note that "on" is in lower case.  Since writing "on"
' doesn't do much good, I simply check for it to determine
' which branch of the conditional to execute.  I could
' place whatever code I wanted inside either condition.
' In this case I simply print out a "user-friendly" message.
If Request.QueryString("default") = "on" Then
	Response.Write "Enabled"
Else
	Response.Write "Disabled"
End If
%>
</strong>.
</p>
<p><strong>Radio Button With An Associated Value</strong></p>
<p>
If you don't like the fact that the radio button returns the
value of "on" it's really easy to change.  Simply
add a value parameter and assign to it what you'd like the
value returned by the radio button to be.
The Radio Button With An Associated Value returned:
<strong><%= Request.QueryString("value_specified") %></strong>.
</p>
<p><strong>Multiple Radio Buttons With The Same Name</strong></p>
<p>
Similarly to the checkbox, the scenario where you have a set
of radio buttons all with the same name is probably one of the
most useful ways to use this type of input tag.  The main
difference is that instead of allowing a user to specify
multiple answers to one question, the radio button element
ensures that one and only one selection is choosen from among
the group of buttons that share a common name.
Multiple Radio Buttons With The Same Name ensured that only one
choice was selected and it was:
<strong><%= Request.QueryString("multiple") %></strong>.
</p>
<p><strong>Radio Button Which Maintains Its State</strong></p>
<p>
At this point there's really nothing different about
this radio button from any other, but I thought I should
illustrate the technique when building the form
(see the form generating section of the source code)
because it's so useful in real life.  In particular, when
you're sending a user back to the form to check their
entries, it's really frustrating for them if they have
to re-enter all their values and re-select all the appropriate
radio buttons.
</p>
<p>
In terms of the value, like I said, this is just like the
standard radio button, but just to keep up the pattern...
Radio Button Which Maintains Its State returned:
<strong><%= Request.QueryString("state_keeper") %></strong>.
</p>
<%
' Here's a little function that you might find handy.
' It takes the name parameter of the radio button you want
' to check and will return a boolean indicating if a
' radio button with that name was enabled on the form when
' the user submitted it even if the value of the
' radio button isn't set to anything.  It works well to
' help simplify your code... especially in conditionals.
Function IsChecked(strFieldName)
  Dim blnChecked
  If Request.QueryString(strFieldName).Count > 0 Then
    blnChecked = True	
  Else
    blnChecked = False
  End If
  IsChecked = blnChecked
End Function
' For example, using the state_keeper example above:
'If IsChecked("state_keeper") Then
'  ' The radio button was enabled.
'End If
%>

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