VB Script

By:

Satish Sukumaran

Brief about VB Script• VBScript stands for Visual Basic Scripting, is a scripting language was launched by Microsoft in1996.

VB Scripting language is a lightweight programming language.

VBScript can be used to write both client-side and server-side scripting.

Data Types• VBScript supports only one Data type called ‘Variant’

•A Variant is a special type of data that can contain different kinds of information, depending upon how it is used.•A variant behaves as a number when it is used in a numeric context and as a string when used in string context.

VBScript VariablesA variable is a "container" /Placeholder that refers to a memory

location,that stores program information that may change at run time.

Variable Declaration:

Dim :Variable declared with Dim at script level are available

To all procedures within the script.

Public: Variables are available to all procedures in all scripts.

Private: Variables are available only to the scripts in which they

are declared.

Naming Rules: Must begin with an alphabetic character Cannot contain an embedded period Cannot exceed 255 characters Must be unique within its scope in which it is declared.

Implicit Declaration:

You can Assign a Value to variable directly (without declaring a variable). But not a good practice, because you may misspell the variable name in one or more places, causing unexpected result when your script is run.

Option Explicit :Option Explicit to avoid incorrectly typing the name of an existing variable.

Example:Option explicitDim var_ xvar_x=1

ConstantsThe values that do not alter during the entire

execution of the program are called as constants.

Const keyword is used to declare constants.It is necessary to initialize the Constant

during its declaration. You cannot change the value of constants in

later script.Syntax:

const x=1 const my string=“This is my string”

Arrays

A Variable containing single value is called scalar variable.

Sometimes 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.

Arrays (cont.)The declaration of an array variable uses

parentheses ( ) following the variable name.

Example:

dim names(2)

names(0)=“Ali“names(1)=“Imran“names(2)=“Khan"

Arrays (cont.)

An array can be multi dimensional.

There can be 60 (maximum) dimensions in an array.

Multiple dimensions are declared by separating the numbers in the parentheses with commas.

ProceduresA Sub procedure:is a series of statements, enclosed by the Sub

and End Sub statements can perform actions, but does not return a

value can take arguments that are passed to it by a

calling procedure without arguments, must include an empty

set of parentheses ()

Procedures (Cont)Sub Keyword is Used to declare a procedure.End Sub Keyword is Used to defining the ending

boundary of a procedure.Call Keyword is Used in order to invoke a

procedure.

Syntax:Sub mysub()

some statements End Sub

Call mysub()

Procedures (Cont)Procedure can take arguments that are

passed to it by calling that procedure .

Syntax:Sub procedure name(arg1,arg2)

some statements End Sub

Call mysub(value1,value2)

FunctionsA Function procedure:is a series of statements, enclosed by the

Function and End Function statements can perform actions and can return a value can take arguments that are passed to it by a

calling procedure without arguments, must include an empty

set of parentheses () returns a value by assigning a value to its

name

Functions (Cont)Function Keyword is Used to declare a Function.End Function Keyword is Used to defining the

ending boundary of a Function.<Function Name> is Used in order to invoke a

Function.

Syntax:Function myfunc()

myfunc=valuesome statements

End Function

myfunc

If ConditionUsing If statement we can execute a single or

block of statements when a condition     is true.

Ex:-                                  If  i=0 Then                                     msgbox "Hello"                                          i=i+1                                  End If

If-Else ConditionExecute a block of statement when condition is

true, otherwise execute another block of statements when condition false.

If i=2 thenmsgbox”Hello world”ElseMsgbox”Thank You”End if

If-Elseif Condition (cont.)Decide among several alternates.

if payment="Cash" then msgbox "You are going to pay cash!" elseif payment="Visa" then msgbox "You are going to pay with visa." elseif payment="AmEx" then msgbox "You are going to pay with American

Express." else msgbox "Unknown method of payment.“ end If

Select Case ConditionUsing this statement one of several groups of statements

are executed based on the expression value. Example: You can use the SELECT statement if you want to select one of many blocks of code to execute.

Select case payment    Case " Cash "    msgbox " You are going to pay cash "   Case " Visa "   msgbox " You are going to pay with Visa "   Case " AmEx"   msgbox " You are going to pay with American Express"   Case Else   msgbox " Unknown method of payment"End Select                  

For LoopA For loop is used for situations when you need to do something over and over again until some condition statement fails.

Ex:-

For count=0 to 3       Print (count)Next

For Each LoopIt is useful when you want to go through every

element in an array but you do not   know how many elements are there inside the array.

Ex:-

Dim a(2)a(0)= " Pen "a(1) =" Register" a(2)= " Copy"For Each item In a   Print(item)Next

Do-while loopDo-while keywords are used to execute

specified code for a set of times (until a condition remains true or a condition becomes false).

Syntax

Do While <Condition for loop>Some Statements

Loop

Do-while loop (cont.)

Do-While can also used in following syntax:

Do some Statements

Loop While i>10

Do-Until Loop Do – Until keyword is used for repeating

some set of statements until a certain condition is true.

Syntax:Do Until <Condition>

some statmemts

Loop

Do-Until Loop (cont.)Do-Until can also used in following syntax:

Do some statements

Loop Until <Condition>

Built in FunctionsVB Script provides several built in functions

that can be used just by calling them.

Few Examples:

DateTimeInt

Thank You !