Variables and Expressions in VBScript

ASP Tutorials - Herong's Tutorial Examples

∟Variables and Expressions in VBScript

This section provides tutorial examples on how to use variables and expressions in VBScript language.

Special rules about variables and expressions:

Variables used without declarations are called "variant" variables.
Variant variables can be used to store different data types.
Variable names are case insensitive.
"=" is the assignment operator. But it is also the Boolean equality operator.
"&" is the string concatenation operator.

Here is a sample ASP page, variable.asp:

<script language="vbscript" runat="server">
'  variable.asp
'  Copyright (c) 2002 by Dr. Herong Yang
'  This program demonstrates some special rules about variables and 
'  expressions.
'
   response.write("<html><body>")
   response.write("<b>Tests on variables</b>:<br/>")
   i = 1 + 2 + 3
   s = "Sum = "
   s = s & i & "<br/>"
   i = i=6
   response.write(s)
   response.write("Is the answer correct? " & i)
   response.write("</body></html>")
</script>

Output:

Tests on variables:
Sum = 6
Is the answer correct? True

"i = i=6" is a very unusual statement. First of all, variable "i" has changed its data type from integer to Boolean. Secondly, two "=" signs are used next to each other, the first one is an assignment operation, and the second one is a Boolean equality operator.