Toggling a value between 1 and 0

by lgasoft 18. September 2009 05:46

Sometimes you are in the need of toggling a value in a loop.
This could for example be used for changing the css class in a list, a different class name for each item in the list.

So, how do you do this?

It’s really rather easy, let’s look at the following code:

Dim i ‘As Integer
i = 1
i = 1 – i
The result of the above calculation is of course 0.

So, now i equal 0

Let’s do it again:
i = 1 – i

And now i equal 1

Let’s do it again:
i = 1 – i

And suddenly i equal 0 again.

Now we have the logic clear to us, let’s try it in a real programming situation.

Create an .asp file and paste the following code into it, then put the .asp file in your web server and point your browser towards it.

<%@ Language="VBScript"%>
<%Option Explicit%>
<%
With Response
      .Buffer=true
      .Expires=0
      .Clear
End With
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
   <title>Toggle Value</title>
   <meta http-equiv="Content-Type" content="text/html; charset=utf-8"">
<style type="text/css">
body {
background-color: #FFFFFF;
font-family: Verdana, Geneva, Arial, Tahoma, sans-serif;
font-size: 80%;
}
div {
border: solid 1px #505050;
margin-bottom: 3px;
padding: 4px;
width: 200px;
}
.div0 {
background-color: #E3E3E3;
}
.div1 {
  background-color: #F4F4F4;
}
</style>
</head>
<body>
<%
Dim i
Dim y

i = 0
For y = 1 To 12
  Response.Write("<div class=""div" & i & """>" _
  & "Div:" & y & " [i = " & i & "]</div>" & VbCrLf)
  i = 1 - i
Next
%>
</body>
</html>

If all went well you should see something like this in your browser.