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Vb Script Variable Assignment

ASP Variables

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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>

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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.


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VBScript Variables

by Dale Fugier

This guide provides an overview of VBScript variables.

Overview

A variable is a convenient placeholder that refers to a computer memory location where you can store program information that may change during the time your script is running. For example, you might create a variable called ClickCount to store the number of times a user performs a certain operation. Where the variable is stored in computer memory is unimportant. What is important is that you only have to refer to a variable by name to see or change its value. In VBScript, variables are always of one fundamental data type: Variant.

Declaration

You declare variables explicitly in your script using the statement, the statement, and the statement. For example:

You declare multiple variables by separating each variable name with a comma. For example:

Naming Restrictions

Variable names follow the standard rules for naming anything in VBScript. A variable name:

  • Must begin with an alphabetic character.
  • Cannot contain an embedded period.
  • Must not exceed 255 characters.
  • Must be unique in the scope in which it is declared.

Scope & Lifetime

A variable’s scope is determined by where you declare it. When you declare a variable within a procedure, only code within that procedure can access or change the value of that variable. It has local scope and is a procedure-level variable. If you declare a variable outside a procedure, you make it recognizable to all the procedures in your script. This is a script-level variable, and it has script-level scope.

The lifetime of a variable depends on how long it exists. The lifetime of a script-level variable extends from the time it is declared until the time the script is finished running. At procedure level, a variable exists only as long as you are in the procedure. When the procedure exits, the variable is destroyed. Local variables are ideal as temporary storage space when a procedure is executing. You can have local variables of the same name in several different procedures because each is recognized only by the procedure in which it is declared.

Assigning Values

Values are assigned to variables creating an expression as follows: the variable is on the left side of the expression and the value you want to assign to the variable is on the right. For example:

Scalar Variables & Arrays

Much of the time, you only want to assign a single value to a variable you have declared. A variable containing a single value is a scalar variable. Other times, it is convenient to assign more than one related value to a single variable. Then you can create a variable that can contain a series of values. This is called an array variable. Array variables and scalar variables are declared in the same way, except that the declaration of an array variable uses parentheses following the variable name. In the following example, a single-dimension array containing 11 elements is declared:

Although the number shown in the parentheses is 10, all arrays in VBScript are zero-based, so this array actually contains 11 elements. In a zero-based array, the number of array elements is always the number shown in parentheses plus one. This kind of array is called a fixed-size array.

You assign data to each of the elements of the array using an index into the array. Beginning at zero and ending at 10, data can be assigned to the elements of an array as follows:

Similarly, the data can be retrieved from any element using an index into the particular array element you want. For example:

Arrays aren’t limited to a single dimension. You can have as many as 60 dimensions, although most people can’t comprehend more than three or four dimensions. You can declare multiple dimensions by separating an array’s size numbers in the parentheses with commas. In the following example, the MyTable variable is a two-dimensional array consisting of 6 rows and 11 columns:

In a two-dimensional array, the first number is always the number of rows; the second number is the number of columns.

You can also declare an array whose size changes during the time your script is running. This is called a dynamic array. The array is initially declared within a procedure using either the statement or using the statement. However, for a dynamic array, no size or number of dimensions is placed inside the parentheses. For example:

To use a dynamic array, you must subsequently use to determine the number of dimensions and the size of each dimension. In the following example, sets the initial size of the dynamic array to 25. A subsequent statement resizes the array to 30, but uses the keyword to preserve the contents of the array as the resizing takes place.

There is no limit to the number of times you can resize a dynamic array, although if you make an array smaller, you lose the data in the eliminated elements.


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