vb scripting tutorial

7/28/2019 Vb Scripting Tutorial

1/37

VB ScriptBy:

Ali Imran Khan

[email protected]


2/37

VBScript is a scripting languageScripting language is a lightweight programminglanguage

VBScript is a light version of Microsoft's programming

language Visual Basic

VBScript can be used for both client-side and server-sideprogramming.


3/37

VBScript Variables A variable is a "container" for information you want to store.

Naming Rules:

Must begin with an alphabetic character

Cannot contain a period

Cannot exceed 255 characters

Must be unique within its scope


4/37

Lifetime OF Variables Local Variables:

When you declare a variable within a procedure, the variable can

only be accessed within that procedure. When the procedure

exits, the variable is destroyed. You can have local variables withthe same name in different procedures, because each is

recognized only by the procedure in which it is declared.

Global Variables:

If you declare a variable outside a procedure, all the procedureson your page can access it. The lifetime of these variables startswhen they are declared, and ends when the script is closed.


5/37

Variable (Cont) Declaration:

Dim Keyword is used to Declare a variable

You can Assign a Value to variable directly (without declaringa variable). But not a good practice.

Option Explicit Keyword is used to restrict variables to bedeclared before their usage.

Example:Option explicit

Dim var_ x

var_x=1


6/37

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


7/37

Practical Work !


8/37

ArraysAn array is a set of variables conveniently packages for

easy handling

Sometimes you want to assign more than one value toa single variable. Then you can create a variable that

can contain a series of values. This is called an arrayvariable


9/37

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"


10/37

Arrays (cont.)An array can be multi dimensional.

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

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


11/37

Practical Work !


12/37

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 callingprocedure

without arguments, must include an empty set ofparentheses ()


13/37

Procedures (Cont) Sub Keyword is Used to declare a procedure.

End Sub Keyword is Used to defining the endingboundary of a procedure.

Call Keyword is Used in order to invoke a procedure.

Syntax:

Sub mysub()some statements

End Sub

Call mysub()


14/37

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)


15/37

Practical Work !


16/37

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 callingprocedure

without arguments, must include an empty set ofparentheses ()

returns a value by assigning a value to its name


17/37

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

End Function Keyword is Used to defining the endingboundary of a Function.

is Used in order to invoke a Function.

Syntax:

Function myfunc()some statements

End Function

myfunc


18/37

Practical Work !


19/37

If Condition Ifkeyword is used for executing a set of code when certain

condition is true.

Endifkeyword is used to end the if condition code block.

Syntax:

If then

Some statements

End if


20/37

If-Else Condition if...then...else - use this keyword if you want to select

one of two sets of lines to execute

if...then...elseif- use this keyword if you want toselect one of many sets of lines to execute


21/37

If-Else Condition (cont.)

Syntax :

if thenSome statements

Else

Some statements

end If


22/37

If-Elseif Condition (cont.)

Syntax :

if thenSome statements

Elseif then

Some statements

Else

Some statements

end If


23/37

Practical Work !


24/37

Select Case Condition Selectcasekeyword is used to execute one of many blocks of code.

Syntaxselect case

case Some statements

case Some statements

case Else

Some Statementsend select


25/37

Practical Work !


26/37

For Loop For loop is used to execute set of statements , pre

defined number of iterations.

For Next keywords are used to implement the ForLoop.

Syntax:

For to Some Statements

Next


27/37

For Loop (cont.) Stepkeyword is used to increase or decrease the

counter variable by the specified value.

Syntax

For To Step

some statements

Next


28/37

For Loop (cont.)You can use for loop in order to repeat a block of code for

each item in a collection, or for each element of an array.

Syntax:

For Each in

Next


29/37

Practical Work !


30/37

Do-while loop Do-whilekeywords are used to execute specified code

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

Syntax

Do While Some Statements

Loop


31/37

Do-while loop (cont.)

Do-Whilecan also used in following syntax:

Do

some Statements

Loop While i>10


32/37

Do-Until Loop Do Until keyword is used for repeating some set of

statements until a certain condition is true.

Syntax:

Do Until

some statmemts

Loop


33/37

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

Dosome statements

Loop Until


34/37

Practical Work !


35/37

Built in Functions

VB Script provides several built in functions that canbe used just by calling them.

Few Examples:

Date

Time Int


36/37

Practical Work !


37/37

Thank You !

vb scripting tutorial

Documents