VB Script By: Ali Imran Khan
[email protected]
•
VBScript is a scripting language
Scripting language is a lightweight programming language •
VBScript is a light version of Microsoft's programming language Visual Basic •
VBScript can be used for both client-side and server-side programming. •
•
VBScript is a scripting language
Scripting language is a lightweight programming language •
VBScript is a light version of Microsoft's programming language Visual Basic •
VBScript can be used for both client-side and server-side programming. •
VBScriptt Variable VBScrip ariabless
A variable is a "container" for information information you want to store.
Naming Rules: Rules:
Must begin with an alphabetic character
Cannot contain a period
Cannot exceed 255 characters
Must be unique within its scope
Lifetime OF 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 with the same name in different procedures, because each is recognized only by the procedure in which it is declared.
Local Variables:
Global Variables:
If you declare a variable outside a procedure, all the procedures on your page can access it. The lifetime of these variables starts when they are declared, and ends when the script is closed.
Variable (Cont)
Declaration:
Dim Keyword is used to Declare a variable You can Assign a Value to variable directly (without declaring a variable). But not a good practice. Option Explicit Keyword is used to restrict variables to be declared before their usage.
Example: Option explicit Dim var_ x var_x=1
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
Practical Work !
Arrays
An array is a set of variables conveniently packages for easy handling 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.
Practical Work !
Procedures A 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)
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Functions A 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. is Used in order to invoke a Function.
Syntax:
Function myfunc() some statements End Function myfunc
Practical Work !
If Condition
If keyword is used for executing a set of code when certain condition is true. Endif keyword is used to end the if condition code block.
Syntax:
If then Some statements End if
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 to select one of many sets of lines to execute
If-Else Condition (cont.)
Syntax :
if then Some statements Else Some statements end If
If-Elseif Condition (cont.)
Syntax :
if then Some statements Elseif then Some statements Else Some statements end If
Practical Work !
Select Case Condition
Select case keyword is used to execute one of many blocks of code.
Syntax select case case Some statements
case Some statements ……… ………
case Else Some Statements end select
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For Loop
For loop is used to execute set of statements , pre defined number of iterations. For … Next keywords are used to implement the For Loop. Syntax: For to Some Statements Next
For Loop (cont.)
Step keyword is used to increase or decrease the counter variable by the specified value.
Syntax
For To Step some statements Next
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
Practical Work !
Do-while loop
Do-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 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 some statmemts
Loop
Do-Until Loop (cont.)
Do-Until can also used in following syntax: Do some statements Loop Until
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Built in Functions
VB Script provides several built in functions that can be used just by calling them. Few Examples:
Date Time Int
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