Explanation of VBScript for use in HP QuickTest Professional (QTP)

1) VBScript in QTP

Scripting language for QuickTest Professional (QTP) is VBScript.

VBScript (short form of Visual Basic Scripting Edition) is a lively scripting language interpreted via

Microsoft's Windows Script Host.

VBScript has many powerful functions and provides excellent support for variables, data types, and error

handling.

Two script engines can interpret VBScript- VBScript.dll, which is invoked by asp.dll is used in web

environment and Wscript.exe & Cscript.exe in Windows GUI environment using Windows Script Host

(WSH).

We typically, use VBScript within WSH to automate systems administration tasks. WSH is the system

module that transforms a VBScript file into a Windows executable file.

Wscript.exe is used to display output and receive input in Windows GUI format such as dialog and input

boxes.

Cscript.exe is used in a command-line environment. When VBScript source code is contained in

standalone files, they have the file extension .Vbs.

2) VBScript Data Type

VBScript has only one data type called a Variant that can store any type of value. A Variant is a special kind

of data type that can contain different kinds of information, depending on how it is used.

Suppose if you’re using a variable for assigning a numeric value, that variable behaves like a numeric data

type. If you assign string value, that variable behaves like a string.

VBScript contains following subdatatypes in the Variant.

1) Empty

2) Null

3) Boolean

4) Byte

5) Integer

6) Currency

7) Long

8) Single

9) Double

10) Date (Time)

11) String

12) Object

13) Error

We can use conversion functions to convert data from one sub-data type to another type. To find

subdatatype of a variant we need to use vartype function.

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3) VBScript Variable

A variable is a convenient placeholder to store program information. We can change variable value in script

running time. In VBScript variables are always of one fundamental data type Variant.

Advantage of using Variable in scripts: Variable is quite useful in carrying a value. For example if the

script is using a value 10 in five places (3rd, 7th, 12th, 17th, 20th lines). In case the value is changed from 10

to 20 then we need to change that value in all the places wherever it is used. But if we have used variable in

place of value (x=10) we need to change in only one place if that value is changed from 10 to 20(x=20).

Variables are having flexibility to change value in run time.

Variable names go by the following standard naming conventions 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.

It must be distinctive (unique) within the scope in which it is declared. If we declare a variable inside a

procedure then its scope is local to that Procedure and only code within that procedure can access it, but

if we declare a variable outside a procedure in a script, it is available to all the procedures in a script.

Procedure level variable exits as long as we are in the procedure and a life of a script level variable is the

time it is declare up till the time script finishes.

Variables can be declared explicitly and implicitly.

Explicitly variables are declared with Dim statement, Public Statement, Private Statement.

Dim Name

Dim Name, employee address, city

Implicitly we can declare them within the script by just using the variable name. But this practice is prone

to errors.

We can force VBScript to require all variables to be explicitly declared by including the statement Option

Explicit at the start of every script.

VBScript does not provide support for constants.

From VBScript 5.0 onwards programmers are able to create class constructs in VBScript-A step towards

OOP.

Variables declared by Dim and Public are public in nature (accessible outside of the class). By default

also variables are Public: in nature. With Private we can declare variables not visible outside of the class.

Example of a variable:

Type this in notepad, save the notepad with some name and .html extension (like in c:\program\p.html

where “program” is the name of a folder)

Explanation of VBScript for use in HP QuickTest Professional (QTP)

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<html>

<body>

<script type=”text/vbscript”>

dim variable_name

variable name =”Testing Genius”

document.write(variable_name)

</script>

</body>

</html>

Now open internet explorer and in the address bar type c:\program\p.html and press enter.

Another example that can be tried is:

<html>

<body>

<script type="text/vbscript">

dim variable_ name

variable_name = 2

variable_name = variable_name+1

document.write(variable_name)

</script>

</body>

</html>

Another example of getting input from the user:

Enter- the below code in notepad and save it with .vbs extension (like we saved it as c:\program\q.vbs where

“program” is the name of a folder)

dim variable_ name

variable name =InputBox("Enter your name:")

MsgBox("Your name is " & variable_name)

Now go to command prompt (C:\>) and type program\q and hit enter ( there is no need to type the extension)

4) VBScript Arrays

Array Variable: A variable containing a single value is a scalar variable. we can create a variable that can

contain a series of values using an index number. This is called an array variable. Arrays are useful when we

are storing sets of similar data. We can store any kind of data in an array. The array can hold a combination

of data types.

Arrays are of two types: 1) Fixed Length Arrays 2) Dynamic Arrays

Fixed arrays have a specific number of elements in them, whereas dynamic arrays can vary in the number of

elements depending on how many are stored in the array.

Here we have explained all the ways to initialize and use arrays in VBScript. Every element of an array is

associated with a unique index number. By default, index number starts from 0. The number of elements

in an array is a fixed number. It can also be re-adjusted dynamically.

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Method of creating Fixed Length Arrays:

For Example Dim a(10) : Here 'a' is an array and is having 11 elements (Since array count starts from 0).

Here it's a fixed size array with size 10.

Method of creating Dynamic Arrays:

A dynamic array is created in the same way as a fixed array, but we don't put any bounds in the declaration.

For Example Dim x() : Here 'x' is the dynamic array and we can store n number of elements in it. The benefit

of a dynamic array is that if we don't know how large the array will be when we write the code, we can create

code that sets or changes the size while the VBScript code is running.

Arrays can have multiple dimensions. VBScript supports up to 60.

Example – 1:

Dim variable_name(upper_limit) [As data_type]

If "As data_type" is not specified, it will be a variant. Above we have declared a fixed size array. The array

size limit is upper limit +1 because index starts from 0.

<html>

<body>

<script type-"text/vbscript">

dim e_name (5)

e_name(0)="Himanshu"

e_name(1)="Piyush"

e_name(2)="Neha"

e_name(3)="Manjri"

e_name(4)="Rohit"

e_name(5)="Amar"

for i-0 to 5

document.write(e_name(i) & "<br />")

next

</script>

</body>

</html>

Example – 2:

Dim variable name() [As data-type]

ReDim [Preserve] variable_name(upper_limit)

Firstly we declare an array with no upper limit and then with ReDim we reset the upper bound to a new

value. The optional key word "Preserve" states that all of the old elements must be preserved when

changing the array size.

The size of the dynamic array changes during the time our script is running. The array is initially

declared using either the Dim statement or using the ReDim statement, For a dynamic array, no size or

number of dimensions is placed inside parentheses.

Dim first Array()

ReDim second-Array()

In the following example, ReDim sets the initial size of the dynamic array to 25

ReDim first_Array(25)

We can resize a dynamic array unlimited number of times.

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Dim array-dynamic()

' Size the dimension to contain one dimension with 3 elements

ReDim array_dynamic(2)

Put data in the array

array_dynamic(0)= “1”

array_dynamic(1)= “2”

array_dynamic(2)= “3”

Resize the array, but keep the existing data

ReDim Preserve array_dynamic(5)

' Display the 3rd element

MsgBox array_dynamic(2)

MsgBox displays 3.

Example – 3:

variable_name = Array(element1, element2, ...)

Array function takes values of variant type and returns a dynamic sized array. The arguments are a listing

of values that will become the elements of the array,

Dim a

a=Array(5,10,15,20)

document.write(a(3))

Output: 20

Some of the Array keywords and their uses;

Keyword Function

Dim It will Declare an array

Erase Reinitializes the elements if it is a fixed-size array and

deallocates the memory used if it is a dynamic array.

IsArray This will Return True if A is an array, False if it is not

LBound This will Return lower hound of an array, in VBScript it will

always return 0

Preserve Preserve (Optional) is used to preserve the data in an

existing array, when you resize it.

ReDim This is used to size or resize a dynamic array.

UBound This will Return all upper- bound of array

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5) VBScript Constants

A constant is a meaningful name that takes the place of a number or string and never changes. The

difference between variable and constant is we can change the variable value in run time but for constants its

not possible.

How do we create constants?

For Example: const str="QTPGENIUS" : Here ”str” is a constant and the value will never change.

We have two types of constants 1) Public constants 2) Private constants.

By default all constants are Public. However we can specify the type if required

For Example: Public const str="QTPGENIUS"

or

For Example: Private const str="QTPGENIUS"

6) VBScript Functions and Subroutines

There are two types of procedures in VBScript

1) Function Procedure: It is a series of VBScript statements enclosed by the Function and End Function

statements. In Function procedures we can use function name to assign a value. Function Procedure is able

to return the value.

For example:

Function demo_add(a,b)

demo_add=a+b

End Function

oVal=demo_add(2,3)

msgbox oVal 'Returns 5

In this example demo_add function returns a value to oVal.

2) Sub Procedure: It is a series of VBScript statements enclosed by the Sub and End Sub statements.

Sub Procedure cannot return any value.

For example:

Sub demo_sub(a,b,c)

c=a+b

End sub

demo_sub 2,3,x

msgbox x 'Returns 5

This example will do the same as what function procedure is doing above. But in sub Procedure we need to

use one more parameter to get values from the sub procedure.

The main difference between a function and a subroutine is that a subroutine will do some processing of

the code and then quit; while a function processes some code and then returns the result back.

VBScript functions are described using the Function and End Function keywords.
<html>
<body>
<script type=”text/vbscript”>
FUNCTION add2numbers
Result . 2 + 2
add2numbers = Result
END FUNCTION
document.write(add2numbers)
</script>
</body> </html>