VBScript - Most Popular Scripting Language

8/11/2019 VBScript - Most Popular Scripting Language

1/19

VB Script

1


2/19

Subjects forSession

Vbscript fundamentals.

Variant subtypes.

Variables.

Option Explicitstatement.

Keywords.

Scope and liftime of variables.

Dim, Privateand Publicstatements.

Remstatement.

2


3/19

What is VBScript?

A Safe subset of visual basic

The VBScript ode is case !nsensitive.

"icrosoft Visual Basic Scriptin# $dition brin#sactive scriptin# to a wide variety of environments,includin# Web client scriptin# in "icrosoft !nternet$%plorer and Web server scriptin# in "icrosoft!nternet !nformation Service &!!S'.

3


4/19

"icrosoft( Script Timeline

4

!nternet

$%plorer ).*+-

Version/.* Version0.*

!!S 0/0-

!nternet$%plorer 1.*

+-2

Version).*

Windows-+

Version)./ Version1.*Version3.*

VisualStudio !nternet$%plorer 3.*

Win 4T 3.*

4ote5 6uic7Test uses VBScript 3.


5/19

Scriptin# for Speci8c 9latforms

VBScript

: desi#ned to run on multiple platforms that use theActive; Scriptin# !nterface.

VBA &VB for Applications': "ore sophisticated customi


6/19

VBScript has only one data type called a Variant.

A Variantis a special 7ind of data type that cancontain di=erent 7inds of information, dependin# onhow it is used.

Because Variantis the only data type in VBScript, itis also the data type returned by all functions inVBScript.

At its simplest, a Variantcan contain either numericor strin# information.

A Variantbehaves as a number when you use it in anumeric conte%t and as a strin# when you use it in astrin# conte%t.

6


7/19

VBScript >ata TypesVariant Subtypes

Beyond the simple numeric or strin# classi8cations, aVariantcan ma7e further distinctions about thespeci8c nature of numeric information.

or e%ample, you can have numeric information thatrepresents a date or a time.

When used with other date or time data, the result isalways e%pressed as a date or a time.

@ou can also have a rich variety of numeric informationran#in# in si


8/19

VBScript >ata TypesVariant Subtypes

8

Subtype Description

$mpty Variantis uninitiali


9/19

Variables

A variable is a convenient placeholder that refers to acomputer memory location where you can storepro#ram information that may chan#e durin# thetime your script is runnin#.

or e%ample, you mi#ht create a variable calledlic7ount to store the number of times a user clic7san obHect on a particular Web pa#e.

you only have to refer to a variable by his name to

see or chan#e its value.

9


10/19

>eclarin# Variables

@ou declare variables e%plicitly in your script usin# theDimstatement, the Publicstatement, and the Privatestatement. or e%ample5

Dim>e#reesahrenheit

@ou declare multiple variables by separatin# eachvariable name with a comma. or e%ample5

DimTop, Bottom, Deft, Ii#ht

10


11/19

>eclarin# Variables

@ou can also declare a variable implicitly bysimply usin# its name in your script.

That is not #enerally a #ood practice because

you could misspell the variable name in one ormore places, causin# une%pected results whenyour script is run.

or that reason, the Option Explicitstatement is available to reJuire e%plicit

declaration of all variables.

11


12/19

Gption $%plicit Statement

orces e%plicit declaration of all variables in a script.

!f used, the OptionExplicitstatement must appearin a script before any other statements.

When you use the OptionExplicitstatement, youmust e%plicitly declare all variables usin# the Dim,Private, Public, or ReDimstatements. !f youattempt to use an undeclared variable name, an erroroccurs.

Tip se OptionExplicitto avoid incorrectly typin#the name of an e%istin# variable or to avoid confusionin code where the scope of the variable is not clear.

12


13/19

"ust be#in with an alphabetic character.

annot contain an embedded period.

"ust not e%ceed 033 characters.

"ust be uniJue in the scope in which it is

declared.

13

Tip meanin#full pre8% to variables to indicate thesubtypes i.eiounter &inte#er', str4ame &Strin#', bla# &Boolean',dteToday &>ate'


14/19

$mpty: The Empty7eyword is used to indicate an uninitiali


15/19

A variableLs scope is determined by where you declare it.

When you declare a variable within a procedure, only code within thatprocedure can access or chan#e the value of that variable.

!f you declare a variable outside a procedure, you ma7e it reco#ni


16/19

DimvarnameM!MsubscriptsN"NM# varnameM!MsubscriptsN"NN $ $ $

>eclares variables and allocates stora#e space.

Variables declared with Dimat the script level are available to allprocedures within the script.

At the procedure level, variables are available only within the

procedure.

@ou can also use the Dimstatement with empty parentheses todeclare a dynamic array.

Note When you use the Dimstatement in a procedure, you

#enerally put the Dimstatement at the be#innin# of the

procedure.

16


17/19

PrivatevarnameM!MsubscriptsN"NM# varnameM!MsubscriptsN"NN $ $ $

>eclares private variables and allocates stora#e space.

9rivate statement variables are available only to the script in whichthey are declared.

The followin# e%ample illustrates use of the Privatestatement5

17

Private"y4umber 9rivate Variant variable.Private"yArray&-' 9rivate array variable. "ultiple 9rivate declarations of Variant variables.Private"y4umber, "yVar, @our4umber


18/19

PublicvarnameM!MsubscriptsN"NM# varnameM!MsubscriptsN"NN $ $ $

>eclares public variables and allocates stora#e space.

Publicstatement variables are available to all procedures inall scripts.

@ou can also use the Publicstatement with emptyparentheses to declare a dynamic array.

18

Public"y4umber 9ublic Variant variable.Public"yArray&-' 9ublic array variable.

"ultiple 9ublic declarations of Variant variables.

Public"y4umber, "yVar, @our4umber


19/19

19

Date post:	02-Jun-2018
Category:	Documents
Upload:	apextgi
View:	233 times
Download:	0 times

VBScript - Most Popular Scripting Language

Documents