Adding
numbers by passing parameters:
<html>
<body>
<script type=”text/vbscript”>
FUNCTION ADD(Number1,
Number2)
Result = Number1 + Number2
ADD = Result
END FUNCTION
document.write(ADD(4, 1))
</script>
</body>
</html>
Function
to get square of a number:
<html>
<body>
<script type=”text/vbscript”>
Function do_square(number)
Do_square = number + number
end function
'first way of calling a
function
document.write(do_square(5))
document.write("
")
'second way of calling a
function
if 90 < do_square(8)
then
document.Write(“90 is less
than 8*8")
else
document.Write("8*8 is
less than 90”)
end if
</script>
</body>
</html>
Explanation
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Page 9 of 23
A Sub procedure is a
series of VBScript statements, enclosed by Sub and End Sub statements
<html>
<body>
<script type=”text/vbscript”>
call square ()
Sub square()
Var1 =
InputBox("Please enter a number", 1)
Msgbox ("The square is
" & do_square(var1))
End Sub
Function do square(number)
do_square = number * number
end function
</script>
</body>
</html>
We have written the
calling statement (call square()) in the script itself.
Passing
variable by reference example:
<html>
<head>
<script type=”text/vbscript”>
sub mysub ( )
dim x
x=2
document.write("in
mysub" & x )
call newsub(x)
document.write("Back
in mysub" & x )
end sub
call mysub()
sub newSub(byref var1)
var1=var1*var1
document.write("in
newsub" & var1)
end sub
</script>
</head>
</html>
This shows that only the
address is being passed that is why it is showing the updated value third time
in
Back in mysub.
Passing
variable by value example:
<html>
<head>
<script type=”text/vbscript”>
sub mysub ( )
dim x
x=2
document.write("in
mysub" & x )
call newsub(x)
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document.write("Back
in mysub" & x )
end sub
call mysub()
sub newSub(byval var1)
var1=var1*var1
document.write("in
newsub" & var1)
end sub
</script>
</head>
</html>
This shows that another
value is being passed as can be seen by the result of the third x as in Back in
mysub.
7)
Arguments in Procedures
There are two types of
arguments in procedures
1) By
Val: Indicates that the argument is passed by value.
2) By
Ref: Indicates that the argument is passed by reference.
By default all arguments
are 'ByRef'.
For example:
Function demo_add(a,b)
demo_add=a+b
End Function
Here ‘a,b’ are the
arguments. By default these are 'ByRef'.
In simple terms ‘ByRef’
Means the value which is assigned to the variable with in the function is
permanent
and we can use that value
out side that function as well.
‘ByVal’ means the value,
which is assigned to the variable with in the function, is temporary and we can
use
that value only with in
that function.
For example:
Function
demo_parameters(byref x,byval y)
x=20
y=50
demo_parameters=x+y
End Function
a=10
b=20
msgbox demo_parameters(a,b)
msgbox a
msgbox b
In the above function ‘x’
and ‘y’ are the arguments, declared as ‘byref’ and ‘byval’. With in that
function we
have assigned values to ‘x’
and ‘y’.
Outside of the function we
have assigned values to two variables and passing those variables in to the
Explanation
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Page 11 of 23
function. Here 'a' is
passing reference to x and b is passing value to y. With in that function we
are changing
the value for ‘x’. This
value is permanent for 'a' - because 'a' is passed as 'ByRef'. But the value of
'b' will not
be changed because it is
passed as 'ByVal'.
8)
VBScript Conditional Statements
Three types of conditional
statements are there in VBScript.
if ...
then ... else statement
Example
of if statement without else:
Example –
1:
if i=2 Then msgbox
"Hello World"
Example –
2:
<script type=”text/vbscript”>
Dim var_num
var_num = 7
If var_num = 7 Then
document.write("You
are a Lucky 7!")
End If
var_num = 2
If var_num = 7 Then
docuxent.write("Hello!")
End If
</script>
Example –
3:
More than one statement
can be executed for truth condition by putting the statements on separate line.
if i=2 Then
msgbox "Hello
World"
i = i+1
end if
Example
of if ….then…. else statement:
Example –
1:
if i=2 Then
msgbox "Hello
World"
else
msgbox "Thank
You"
Example –
2:
<script type=”text/vbscript”>
Dim weight
weight = 50
If weight > 70 Then
document.write("You
are Over Weight")
Else
document.write("Your
Weight is perfect")
End If
</script>
Explanation
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Page 12 of 23
Example
of if ….then…. elseif statement:
Example –
1:
if fee="Cash"
then
msgbox "pay
cash!"
elseif fee="Visa"
then
msgbox "pay with
visa."
elseif fee="American
Express" then
msgbox "pay with
American Express."
else
msgbox "Unknown method
of payment"
End If
</script>
Example –
2:
<script type=”text/vbscript”>
Dim weight
weight = 65
If weight > 70 Then
document.write("You
are Over Weight")
elseIf weight > 60 Then
document.write("Your
Weight is Perfect")
elseIf weight > 50 Then
document.write("You
are under Weight")
Else
document.write("Do
Weight again")
End If
</script>
Select
case statement
Example –
1:
select case fee
case "Cash"
msgbox "pay cash"
case "Visa"
msgbox "pay with
visa"
case "American
Express"
msgbox "pay with
American Express"
case Else
msgbox "Unknown method
of payment"
end select
Example –
2:
<script type=”text/vbscript”>
Dim myName
rnyName =
"Rajesh"
Select case myName
Case "Manoj"
document.write("Are
you there Manoj?"?
Explanation
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Page 13 of 23
Case "Pooja"
document.write(“Hello
Pooja?")
Case " Rajesh"
document.write("How
are you Rajesh ?")
End Select
</script>
Example –
3:
<script type=”text/vbscript”>
Dim myName
rnyName =
"Rajesh"
Select case myName
Case "Manoj"
document.write("How
are you Manoj?"?
Case "Pooja"
document.write(“Where are
you Pooja?")
Case " Rajesh"
document.write("Where
did you go Rajesh ?")
Case Else
document.write("Who
are you?")
End Select
</script>
A single expression
(usually variable) is evaluated once and its value is then compared with the
values for
each case. If there is a
match, the block of code associated with that case is executed. If there is no
match then Else case is
executed.
9)
VBScript Looping Statements
We have four looping
statements in VBScript
For….Next
Statement
Example –
1:
<script type=”text/vbscript”>
For num = 0 to 3
document.write("<br
/>Loop #" & num)
Next
</script>
Loop #0
Loop #1
Loop #2
Loop #3
With the help of Step
keyword, we can increase or decrease the counter by the value specified.
Example –
1:
For i=2 To 8 Step 2
any piece of code
Next
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Example –
2:
For i=8 To 2 Step 2
any piece of code
Next
For Each
... Next statement
It is useful when we don't
know how many elements are there in the array.
Example –
1:
<script
type="text/vbscript">
Dim cupboard (2)
cupboard(0) =
"Trouse"
cupboard(1) =
"Shirt"
cupboard(2) =
"Suit"
document.write("In my
cupboard is:")
For Each y In cupboard
doclment.write(y & “<br>")
Next
</scripts
Example –
2:
dim names(2)
names(0)="Rajan"
names(1)="Suresh"
names(2)="Reena"
For Each x in names
document.write(x & “”)
Next
Do...Loop
It will repeat a block of
code while a condition is True or until a condition becomes True
Example –
1:
Do While i>9
any piece of code
Loop
If i equals 8, the code
inside the loop above will never be executed.
Example –
2:
Do
any piece of code
Loop While i>9
The code inside this loop
will be executed at least one time, even if i is less than 9.
Repeating Code Until a
Condition Becomes True
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Example –
1:
Do Until i=9
any piece of code
Loop
If i equals 9, the code
inside the loop will never be executed.
Example –
2:
Do
any piece of code
Loop Until i=9
The code inside this loop
will be executed at least one time, even if i is equal to 9.
The Exit statement can
only he used within a Do ... Loop control structure to provide an alternate way
to
exit a Do ... Loop.
We must end all Do
statements with Loop or otherwise error message will Pop up. The While and the
Until condition may be
placed after the Do or the Loop.
Some
Examples:
Example –
1:
num = 1
Do
num = num + 1
Loop Until num = 5
Example –
2:
num = 1
Do While num < 5
num = num + 1
Loop
Example –
3:
num = 1
Do
num = num + 1 br>Loop
While num < 5
Exit a Do ... Loop
We can exit a Do ...
Loop statement with the Exit Do keyword.
Example –
1:
Do Until i=9
i=i-1
If i<9 Then Exit Do
Loop
Explanation
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Page 16 of 23
The code inside this loop
will be executed as long as i is different from 9, and as long as i is greater
than
9.
While-Wend
statement
While Loop is a simple
loop that keeps looping while a condition is true
Example –
1:
<script type=”text/vbscript”>
Dim count
count = 9
While count > 0
document.write (count)
document.write
("<br />")
count = count - 1
Wend
document.write("Finish!")
</script>
987654321
Finish!
More VBScript techniques
can be accessed by visiting the following link “10 VBScript techniques”
http://windowsitpro.com/article/articleid/20979/10-more-vbscript-techniques.html
Michael Otey the author of
“10 More VBScript Techniques” states that
“In my June 2001 column, I
shared 10 basic VBScript techniques. For those who want to step up a level
and begin writing
productive administrative scripts, here are 10 more VBScript techniques.
10. On
Error-The On Error statement lets a script trap runtime errors and
continue executing. You can
test for errors in the
script after- each statement has executed. On Error Resume Next
9. InStr -This
function lets you locate a substring in a string. The function returns the
starting position of
the substring or a 0 if
the function doesn't find the string. In
nPos =
InStr("123345", "33")
nPos has a value of 3
because "33" begins in the third position of "123345."
8. The Do
Loop -This basic mechanism far repeatedly executing a set of statements
comes in two forms:
a Do Until Loop and a Do
While Loop. The most important distinction between the two loops is that the
Do Until Loop arrays
executes at least once.
Do Until myValue > 1
Explanation
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Page 17 of 23
myValue = myValue + 1
Loop
7.
Subroutines – Modularizing your code into subroutines lets you organize your
scripts and create
reusable routines. You can
define subroutines anywhere in a script. You use subroutines when you don't
need to return a value to
the calling code. . . .
10)
VBScript Classes
Class Hello-World
Public Sub Say_Hello(Name)
MsgBox "Hello, "
& Name & ", welcome to " & Garden &”.”
End Sub
Public Garden
End Class
Dim MyHello_World
Set MyHello_World = New
Hello_World
MyHello_World.Garden =
"Fountain"
MyHello_World.Say_Hello
"Genius"
Above we have created a
class (Hello _World) and an instance (MyHello_World) of that class. VBScript
uses the Class…End Class
statements to define the contents of the class. The property (Garden) and
procedure (Say Hello) are
also declared within the class. Write the whole code written above in notepad,
save it as .vbs and run
it.
Members within the class
can be declared as private and Public. Private members are only visible within
the class whereas public
members are accessible by any code outside of the class. Public is default.
Procedures (Sub or
Function) declared Public within the class are methods of the class. Public
variables
serve as properties of the
class,
Property Let will allow
code outside of the class to assign a value to a private variable of the class.
Class A
Private name
Public Property Let
assign_name(e_Name)
name = e_Name
End Property
End Class
A Property Let procedure
must accept at least one argument. This procedure can also handle the process
of data validation to
check some validation e.g. if the value you are assigning is more than 5
characters
long or- not.
Property Get will allow
code outside of the class to read the value of a Private property variable.
Class A
Private name
Public Property Let
assign_name(e_Name)
name = e_Name
End Property
Public Property Get
assign_name()
assign_name = name
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End Property
End Class
The Property Get procedure
does not accept any arguments, however VBScript allows you to add an
argument. For this you
have to add an additional argument to the property's corresponding Property Let
or- Property
Set procedure because a Property Let/Set procedure must always have exactly one
more
argument than its
corresponding Property Get procedure.
Property
Set - This is an object property assignment procedure used to assign the
New Property value to
the private object
variable (if the private variable is an object). Following op_sys is an
object read-write
property.
Class Machine
Private obj_oOS
Public Property Set
op_sys(oObj)
Set obj_o0S = oObj
End Property
Public Property Get op_sys(
)
Set op_sys = obj_o0S
End Property
End Class
We can
make a property Read-Only by following two methods:
Method–1:
By writing only a Property Get procedure for the property:
In the absence of a
Property Let procedure, code outside of the class cannot write to the
employeeName
property.
Class employee
Private ename
Public Property Get
employeeName()
employeeName = ename
End Property
End Class
Method–2:
By declaring the Property Get procedure as Public and the Property Let
procedure as
Private:
Class employee
Private ename
Private Property Let
employeeName(strName)
ename = strName
End Property
Public Property Get
employeeName()
employeeName = ename
End Property
End Class
Class
Methods:
Where functions or
procedures are written inside the class they are called methods.
If a class method is
declared as Public there it will be available to code outside or inside the
class, and a
method that is declared as
Private will be available only to code inside the class.
Explanation
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Page 19 of 23
Class welcome
Private ur_name
Public Property Let
Name(var-_name)
ur_name =var_name
End Property
Public Sub
Showwelcome(var_type)
MsgBox
Makewelcome(var_type) & Ur_name & “.”
End Sub
Private Function
Makewelcome(var_type)
Select Case var_type
Case '"Formal"
Makewelcome =
"welcome,”
Case "Informal"
Makewelcome = "Hello
there, "
Case "Casual"
Makewelcome = "Hey,
"
End Select
End Function
End Class
Dim my_object
Set my_object = New welcome
With my_object
.Name = “Genius"
.Showwelcome
"Informal"
.Showwelcome “Formal"
.Showwelcome “Casual"
End With
Set my_object = Nothing
Class
Events:
Class_Initialize and
Class_Terminate are associated with every class that we create.
Class_Initialize is
used whenever an object
based on a class is. instantiated. e.g.
Set objectname = New
classname
Class_Initialize
event's general format is:
Private Sub
Class_Initialize( )
'Initialization code goes
here
End Sub
The Class Terminate event
is used when the object goes out of scope, or when the object is set to othing.
Class
Terminate event's general format is:
Private Sub
Class_Terminate( )
'Termination code goes here
End Sub
Explanation
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Page 20 of 23
Another
example of a class:
<html>
<head>
<script
type="text/vbscript">
Class calculator
Public Function
add(var_first, var_second)
Dim output
output = var_first +
var_second
add = output
End Function
Public Function
subtract(sub_first, sub_second)
Dim output
output = sub_first –
sub_second
subtract = output
End Function
End Class
Dim calc_Object
Dim var_addition
Dim var_subtract
Set calc_object = New
calculator
var_addition = calc
Object_add(1,2)
var_subtract = calc
Object.subtract(2,1)
document.write
(var_addition)
document.write
(var_subtract)
</script>
</body>
</html>
Below we will see file
system objects of VBScript which allows us to access, copy, open, delete (and
much more) files on the
operating system.
http://msdn2.microsoft.com/en-us/library/aa7ll2l6(VS.71).aspx
Summary of
VBScript Class Concepts
1. It does NOT support
inheritance. So it is not possible to create a Collie class which inherits
characteristics from a Dog
class which inherits characteristics from a Mammal class, etc.
2. It does NOT support
polymorphism. Kind of a related to inheritance, where for example a Dog class
will
"bark" and a Pig
class will "oink" when they are asked to "speak" (in a
class hierarchy where they
inherited the base Speak()
method from the Mammal class, then override that method to implement
animal unique behavior-).
3. It DOES support
encapsulation, an OO technique which conceals how a particular" class is
implemented, independent
from objects that use the class's Public Properties and Methods. Another way
to think about
encapsulation is to say it is the ability to hide implementation details while
sharing higher
level behavior.
In our opinion the lack of
inheritance and polymorphism are not major shortcomings in scripting
environments such as WSH
and especially QTP, where we are not trying to build large complex OO
programs.
Encapsulation is then the
primary reason to consider using VBScript classes. And, with encapsulation
comes namespace control
which permits any number- of class elements to be named for as long as each
of those elements resides
in a different class (i.e. a different namespace).
Explanation
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11)
VBScript- Property Let, Property Get, Property Set
Class properties in
VBScript are used to assign Values to private variable and handle the process
of data
validation.
Property
Let: Which is used by the outside code to store a value in the private
property variable. It is
similar to a procedure in
the sense that it does not return a value. A Property Let procedure Must accept
at least one argument. If
the private variable you are using is an object then the process of assignment
and data validation is
handled by Property bet.
Property
Set: Similar to Property Let but used for object based properties. By
default, the Property Set
Procedure is Public.
To retrieve the value of a
private variable we will retrieve the value of a Property.
Property
Get: This is used by code outside of our class to read the value of a
private property variable. It
is similar to a function
in the sense that it returns a value to the calling code -- this value is the
private
variable value.
The Property comet
procedure does not accept any arguments. We can add an argument to it, but then
we have to add an
additional argument to the property's corresponding Property Let or Property
Set
procedure, because
Property Let/Set procedure must always have exactly one more argument than its
corresponding Property Get
procedure.
If the property get
procedure returns an object then we can use the set statement (but it works
well
without set also) to
return the value.
Class ABC
'Private object
Private var_obj
Public Property Get
username()
Set username = var_obi
End Property
End Class
Read only
Properties have only Property Get procedure
Write-only
properties have only a Property Let or a Property Set procedure
Read-Write
properties have a Property Get procedure and either a Property Let or a
Property Set
procedure
Example -
1 of Property Let, Property Get, Property Set
Following Example, shows a
simple class that defines a private variable, m_var, and a two read-write
properties, one_type and
two_type, the latter of which is an object property.
Class Computer
Private m_var
Private o_var
Public Property Let
one_type(stringtype)
m_var = stringtype
End Property
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Public Property Get
one_type( )
one_type = m_var
End Property
Public Property Set
two_type(cObj)
Set o_var = oobj
End Property
Public Property Get
two_type( )
Set two_type = o_var
End Property
End Class
Example -
2 of Property Set
Here is the syntax for a
Property Set procedure.
Class Main_class
'Private FS_object object
Private var_Obj
Public Property Set FSPRO
(objFSPro)
Set var_Obj = objFSPro
End Property
End Class
For example, here is what
code that is using an object based on the above class might look like.
Dim objMain_class
Dim objFSPro
Set objFSPro
WScript.CreateObject (“Scripting.FS_Object")
Set objMain_class = New
Main_class
Set =objMain_class.FSPro =
objFSPro
Last line uses the Set
Statement when it writes to the FSPro property. This is required because the
Main_class class used a
Property Set procedure for the FSPro property. Without the Set statement at the
beginning of the last
line, VBScript would produce an error. When a property on a class is object
based, it
is typical to use a
Property Set procedure. Most programmers using this class would expect this.
Example -
3 of Property Set
For example imagine we had
a class that contained a private property named ob_var_conn that was
expected to be an ADO
Connection object. This class definition, with the property Set and Property
Get
Statements might look
like:
Class Connect_Class
'Create a private property
to hold our Connection object
Private ob_var_conn
Public Property Get
Connection ()
Set Connection =
ob_var_conn
End Property
Public Property Set
Connection (ob_var_ccnnection)
'Assign the private property
ob_var_conn to ob_var_connection
Set ob_var_conn=
ob_var_connection
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End Property
End Class
The end developer would
use the Property Set statement in the following manner:
'Create an instance of
Connect_ Class
Dim ob_var_class,
ob_var_record
Set ob_var_class= New
Connect_Class
Set ob_var_Connection =
Server.CreateObject{'ADODB.Connection')
'Assign ob_var_Connection
to the Connection property
Set ob_var_class,Connection
= ob_var_Connection
As with the Property Let
statement, the Property Set statement has an optional argument list. This
argument list must be
identical to the corresponding Property Get's argument list.
12)
Example of VBScript - Property Let, Property Get, Property Set
class PencilClass
Private recentPencil,
recentColor
Property Get Pencil ()
Set Pencil = RecentPencil
End Property
Property Set Pencil (x)
Set recentPencil = x
End Property
Property Get Pencilcolor ()
Select Case recentColor
Case 1: Pencilcolor = “Orange”
Case 2: Pencilcolor = “Green”
Case 3: Pencilcolor = “Yellow”
End Select
End Property
Property Let Pencilcolor ()
If x = ”Orange” Then
recentColor =1
Else
If x = ”Green” Then
recentColor =2
Else
recentColor =0
EndIf
EndIf
End Property
End Class
Set one_pencil = New
PencilClass
Set two_pencil = New
PencilClass
One_pencil.Pencilcolor = “Orange”
wscript.echo
One_pencil.Pencilcolor
Set two_pencil,pencil =
One_pencil ‘Invokes Property Set
wscript.echo “1st time”
& one_pencil, pencilcolor
two_pencil.pencil,Pencilcolor
= “Green”
wscript.echo “2nd time”
& one_pencil, pencilcolor
