ASP Variables
Variables are "containers" for storing information.
More Examples
Declare a variable
This example demonstrates how to declare a variable, assign a value to it, and use the value in a text.
Create an array
Arrays are used to store a series of related data items. This example demonstrates how to
create an array that stores names.
Loop through the HTML headings
How to loop through the six headings in HTML.
Time-based greeting using VBScript
This example will display a different message to the user depending on the time on the server.
Time-based greeting using JavaScript
This example is the same as the one above, but the syntax is different.
Create and change a variable
How to create a variable, assign a value to it, and then change the value of it.
Insert a variable value in a text
How to insert a variable value in a text.
Do You Remember Algebra from School?
Do you remember algebra from school? x=5, y=6, z=x+y
Do you remember that a letter (like x) could be used to hold a value (like 5), and that you could use the information above to calculate the value of z to be 11?
These letters are called variables, and variables can be used to hold values (x=5) or expressions (z=x+y).
VBScript Variables
As with algebra, VBScript variables are used to hold values or expressions.
A variable can have a short name, like x, or a more descriptive name, like carname.
Rules for VBScript variable names:
- Must begin with a letter
- Cannot contain a period (.)
- Cannot exceed 255 characters
In VBScript, all variables are of type variant, that can store different types of data.
Declaring (Creating) VBScript Variables
Creating variables in VBScript is most often referred to as "declaring" variables.
You can declare VBScript variables with the Dim, Public or the Private statement. Like this:
Dim x
Dim carname
Now you have created two variables. The name of the variables are "x" and "carname".
You can also declare variables by using its name in a script. Like this:
carname="Volvo"
Now you have also created a variable. The name of the variable is "carname". However, this method is not a good practice, because you can misspell the variable name later in your script, and that can cause strange results when your script is running.
If you misspell for example the "carname" variable to "carnime", the script will automatically create a new variable called "carnime". To prevent your script from doing this, you can use the Option Explicit statement. This statement forces you to declare all your variables with the dim, public or private statement.
Put the Option Explicit statement on the top of your script. Like this:
Option Explicit
Dim carname
carname=some value
Assigning Values to Variables
You assign a value to a variable like this:
carname="Volvo"
x=10
The variable name is on the left side of the expression and the value you want to assign to the variable is on the right. Now the variable "carname" has the value of "Volvo", and the variable "x" has the value of "10".
VBScript Array Variables
An array variable is used to store multiple values in a single variable.
In the following example, an array containing 3 elements is declared:
Dim names(2)
The number shown in the parentheses is 2. We start at zero so this array contains 3 elements. This is a fixed-size array. You assign data to each of the elements of the array like this:
names(0)="Tove"
names(1)="Jani"
names(2)="Stale"
Similarly, the data can be retrieved from any element using the index of the particular array element you want. Like this:
mother=names(0)
You can have up to 60 dimensions in an array. Multiple dimensions are declared by separating the numbers in the parentheses with commas. Here we have a two-dimensional array consisting of 5 rows and 7 columns:
Dim table(4,6)
Assign data to a two-dimensional array:
Example
<html>
<body>
<%
Dim x(2,2)
x(0,0)="Volvo"
x(0,1)="BMW"
x(0,2)="Ford"
x(1,0)="Apple"
x(1,1)="Orange"
x(1,2)="Banana"
x(2,0)="Coke"
x(2,1)="Pepsi"
x(2,2)="Sprite"
for i=0 to 2
response.write("<p>")
for j=0 to 2
response.write(x(i,j) & "<br />")
next
response.write("</p>")
next
%>
</body>
</html>
Show Example »
The Lifetime of Variables
A variable declared outside a procedure can be accessed and changed by any script in the ASP file.
A variable declared inside a procedure is created and destroyed every time the procedure is executed. No scripts outside the procedure can access or change the variable.
To declare variables accessible to more than one ASP file, declare them as session variables or application variables.
Session Variables
Session variables are used to store information about ONE single user, and are available to all pages in one application. Typically information stored in session variables are name, id, and preferences.
Application Variables
Application variables are also available to all pages in one application. Application variables are used to store information about ALL users in one specific application.