|
What is a Variable?
A variable is a "container" for information you want to store. A
variables value can change during the script. You can refer to a
variable by name to see its value or to change its value. In
VBScript, all variables are of type variant, that can
store different types of data.
Rules for Variable names:
· Must begin with a letter
· Can not contain a period (.)
· Must not exceed 255 characters
Declaring Variables
You can declare variables with the Dim, Public or the Private
statement. Like this:
dim name name = some value
Now you have created a variable. The name of the variable is
"name".
You can also declare variables by using its name in your script.
Like this:
name = some value
Now you have also created a variable. The name of the variable
is "name".
However, the last 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. This is
because when you misspell for example the "name" variable to "nime"
the script will automatically create a new variable called "nime".
To prevent your script from doing this you can use the Option
Explicit statement. When you use this statement you will have 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 name name = some value
Assigning Values to Variables
You assign a value to a variable like this:
name = "Hege" i = 200
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 "name" has the value "Hege".
Lifetime of Variables
How long a variable exists is its lifetime.
When you declare a variable within a
procedure,
only code within that procedure can access or change the value
of that variable. When the procedure exits, the variable is
destroyed. These variables are called local variables. You can
have local variables with the same name in different procedures,
because each is recognized only by the procedure in which it is
declared.
If you declare a variable outside a procedure, all the
procedures in your script will recognize it. These variables
exists from the time they are declared until the time the script
is finished running.
Array Variables
Some times you want to assign more than one value to a single
variable. Then you can create a variable that can contain a
series of values. This is called an array variable. The
declaration of an array variable uses parentheses ( ) following
the variable name. 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) = "Ståle"
Similarly, the data can be retrieved from any element using an
index into 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)
EXAMPLES
1. Variables are used to store information. This example
demonstrates how you can create a variable, and assign a value
to it.
Coding
<html>
<body>
<script language="VBScript">
Dim name
name="Jan Egil"
document.write(name)
</script>
</body>
</html>
Output
Jan Egil
2. This example demonstrates how you can insert a variable value
in a text.
Coding
<html>
<body>
<script language="VBScript">
Dim name
name="Jan Egil"
document.write("My name is: " & name)
</script>
</body>
</html>
Output
My name is: Jan Egil
3. Arrays are used to store a series of related data items. This
example demonstrates how you can make an array that store names.
Coding
<html>
<body>
<script language="VBScript">
Dim famname(5)
famname(0) = "Jan Egil"
famname(1) = "Tove"
famname(2) = "Hege"
famname(3) = "Ståle"
famname(4) = "Kai Jim"
famname(5) = "Børge"
For i = 0 to 5
document.write(famname(i) & "<br />")
Next
</script>
</body>
</html>
Output
Jan Egil
Tove
Hege
Ståle
Kai Jim
Børge |