VBScript

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VB Script

(2)

Subjects for

Session

Vbscript fundamentals. Vbscript fundamentals. Variant subtypes. Variant subtypes. Variables. Variables. Option Explicit

Option Explicit statement. statement. Keywords.

Keywords.

Scope and liftime of variables. Scope and liftime of variables. Dim

Dim,, PrivatePrivate and and PublicPublic statements. statements. Rem

(3)

What is VBScript?

•

A Safe subset of visual basic

•

The VBSc

ript ode is case !n

sensitive.

•

"icrosoft Visual Basic Scriptin# $dition brin#s

active 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'.

(4)

"icrosoft

((

_{Script Timeline}

!nternet !nternet $%plorer ).* $%plorer ).* +- +- Version Version /.* /.* Version Version 0.* 0.* !!S 0 !!S 0 /0- /0- !nternet !nternet $%plorer 1.* $%plorer 1.* +-2 +-2 Version Version ).* ).* Windows Windows -+ -+ Version Version )./ )./ Version Version 1.* 1.* Version Version 3.* 3.* Visual Visual Studio 

Studio  _{$%plorer 3.*}_{$%plorer 3.*}!nternet!nternet Win 4T 3.* Win 4T 3.*

4ote5 6uic7Test uses VBScript 3.

(5)

Scriptin# for Speci8c

9latfor

ms

•

:

_{desi#ned to run on}

_{multiple platfor}

_{ms that use the}

Active; Scriptin# !nterface.

•

VBA &VB for Applications'

:

_{"ore sophisticated customi<ation.}

:

_9ow

_{er user}

_{focus, natural up#rade, superb inte#ration}

•

Visual Basic

:

_{Best tool for}

_{distributed clientServer solutions.}

:

(6)

•

• _{VBScript has only one data type called a}_{VBScript has only one data type called a} _Variant_Variant._.

•

• _A_A _Variant_{Variant is a special 7ind of data type that can}_{is a special 7ind of data type that can}

contain di=erent 7inds of

contain di=erent 7inds of information, dependin# oninformation, dependin# on how it is used.

how it is used.

•

• _Because_Because _Variant_{Variant is the only data}_{is the only data type in VBScript, it}_{type in VBScript, it}

is also the data

is also the data type returned by all functions intype returned by all functions in VBScript.

VBScript.

•

• _{At its simplest, a}_{At its simplest, a} VariantVariant can contain either numeric_{can contain either numeric}

or strin# information. or strin# information.

•

• _A_A _Variant_{Variant behaves as a number when you use it in a}_{behaves as a number when you use it in a}

numeric conte%t and as a strin# when you use it in a numeric conte%t and as a strin# when you use it in a strin# conte%t.

(7)

VBScript >ata Types

V

ariant

Subtypes

•

• Beyond the simple numeric or strin# classi8cations, aBeyond the simple numeric or strin# classi8cations, a

Variant

Variant can ma7e further distinctions about the can ma7e further distinctions about the speci8c nature of numeric information.

speci8c nature of numeric information.

•

• _{or e%ampl}_{or e%ampl}_{e, you can ha}_{e, you can ha}_{ve numeric information that}_{ve numeric information that}

repre

represents a date or sents a date or a time.a time.

•

• _{When used with other date or}_{When used with other date or time data, the result is}_{time data, the result is}

always e%pressed as a date or a t

always e%pressed as a date or a time.ime.

•

• _@_@_{ou can also have a rich variety of numeric inform}_{ou can also have a rich variety of numeric information}_ation

ran#in# in si<e from Boolean values to h

ran#in# in si<e from Boolean values to hu#e oatin#u#e oatin# point numbers.

(8)

VBScript >ata Types

V

ariant

Subtypes

Su

Subtbtypype e DeDescscririptptioionn $mpty

$mpty VariantVariant is uninitiali<ed. Value is * is uninitiali<ed. Value is * for numeric variables or a <erolen#th strin# &CC' for strin# for numeric variables or a <erolen#th strin# &CC' for strin# variables.variables.

4ull

4ull VariantVariant intentionally contains no valid intentionally contains no valid data.data. Boolean

Boolean ontains eitherontains eitherTrueTrue or orFalseFalse.. Byte

Byte ontains inte#er in the ran#e * to 033.ontains inte#er in the ran#e * to 033. !nte#er

!nte#er ontains inte#er in the ran#e )0,2+ to ontains inte#er in the ran#e )0,2+ to )0,22.)0,22. urrency

urrency -00,))2,0*),+3,122.-00,))2,0*),+3,122.3+*+ 3+*+ to to -00,))2,0*),+3,122.3+*-00,))2,0*),+3,122.3+*2.2. Don#

Don# ontains inte#er in the ran#e 0,/12,1+),1+ to 0,/12,1+),12.ontains inte#er in the ran#e 0,/12,1+),1+ to 0,/12,1+),12. Sin#le

Sin#le ontains a sin#leprecision, oatin#point number in the ontains a sin#leprecision, oatin#point number in the ran#e ).1*0+0)$)+ to /.1*/0-+$13 forran#e ).1*0+0)$)+ to /.1*/0-+$13 for ne#ative valuesE /.1*/0-+$13 to ).1*0+0)$)+ for

ne#ative valuesE /.1*/0-+$13 to ).1*0+0)$)+ for positive values.positive values. >ouble

>ouble ontains a doubleprecision, oatin#point number in the ontains a doubleprecision, oatin#point number in the ran#e /.2-2-)/)1+0)0$)*+ toran#e /.2-2-)/)1+0)0$)*+ to 1.-1*313+1/012$

1.-1*313+1/012$)01 for )01 for ne#ative valuesE 1.-1*313+1/012$)01 to /.2-2-)/)1+0)0$)*+ forne#ative valuesE 1.-1*313+1/012$)01 to /.2-2-)/)1+0)0$)*+ for positive values.

positive values.

>ate

>ate ontains a number that represents a date between Fanuary /, /** to >ecember )/, ----.ontains a number that represents a date between Fanuary /, /** to >ecember )/, ----. Strin#

Strin# ontains a variablelen#th strin# that can be up ontains a variablelen#th strin# that can be up to appro%imateto appro%imately 0 billy 0 billion characters in len#th.lion characters in len#th. GbHect

(9)

Variables

•

A variable is a convenient placeholder that refers to a

computer memory location where you can store

pro#ram inform

pro#ram information that may

ation that may chan#e durin# the

chan#e durin# the

time your script is runnin#.

•

_{or e%am}

_{or e%ample, you mi#ht create a}

_{ple, you mi#ht create a}

_{variable called}

lic7ount to store the number of times a user clic7s

an 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.

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>eclarin

# V

ariables

•

@

ou declar

e variables e%p

licitly in your scri

pt usin# the

Dim

statement, the

Public

statement, and the

Private

statement. or e%ample5

Dim

>e#rees

ahrenheit

•

@

ou declar

e multiple variables

by separatin# eac

h

variable name with a comma. or e%ample5

Dim

(11)

>eclarin

# V

ariables

•

@

ou can also declar

ou can also declare a variable impli

e a variable impli

citly by

simply usin# its name in your script.

•

That is not #eneral

That is not #enerally a #ood practice becau

ly a #ood practice because

se

you could misspell the variable name in one or

more places, causin# une%pected results when

your script is run.

•

or that reason, the

Option Explicit

statement is available to reJuire e%plicit

declaration of all variables.

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Gption $%plicit Statement

•

or

ces e%plicit declaration of

ces e%plicit declaration of all variables in

all variables in a script.

a script.

•

!f used, the

Option

Explicit

statement must appear

in a script before any

in a script before any other statements.

other statements.

•

_{When you use the}

_Option

_Explicit

_{statement, you}

must e%plicitly declare all variables usin# the

Dim

,

Private

,

Public

, or

ReDim

statements. !f you

attempt to use an

attempt to use an undeclared variable name, an error

undeclared variable name, an error

occurs.

•

Tip

se

Option

Explicit

to avoid incorrectly typin#

the name of

the name of an e%istin# variable or to avoid confusion

an e%istin# variable or to avoid confusion

in code where the scope of the variable is not clear.

(13)

•

"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.

Tip

meanin#full pre

8% to

variables to indicate t

he

subtypes i.e

iounter &inte#er', str4ame &Strin#',

bla# &Boolean',

dteToday &>ate'

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•

_$mpty

:

: _The_The _Empty_Empty_{7eyword is used to indicate an uninitiali<ed}_{7eyword is used to indicate an uninitiali<ed}

variable value.

•

_4ull

:

: _The_The _Null_Null_{7eyword is used to indicate that a variable contains}_{7eyword is used to indicate that a variable contains}

no valid data.

•

_T

_rue

:

: _The_The _True_True_{7eyword has a value eJual to /.}_{7eyword has a value eJual to /.}

•

_alse

:

: _The_The _False_False_{7eyword has a value eJual to *.}_{7eyword has a value eJual to *.}

•

4othin#

:

: _The_The _Nothin_Nothin_{7eyword in VBScript is used to disassociate an}_{7eyword in VBScript is used to disassociate an}

obHect variable from any actual obHect.

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•

• _{A variableLs scope is determined by where you declare it.}_{A variableLs scope is determined by where you declare it.}

•

• _{When you declare a variable within}_{When you declare a variable within a procedure, only code within that}_{a procedure, only code within that}

procedur

procedure can access or e can access or chan#e the value of tchan#e the value of that variable.hat variable.

•

• _{!f you declare a}_{!f you declare a variable outside a}_{variable outside a procedur}_{procedure, you ma7e it reco#ni<able to all}_{e, you ma7e it reco#ni<able to all}

the procedures in your script. the procedures in your script.

•

• _{The lifetime of a variable dep}_{The lifetime of a variable depends on how lon# it e}_{ends on how lon# it e%ists.}_%ists.

•

• _{The lifetime of a scriptlevel}_{The lifetime of a scriptlevel variable e%tends fr}_{variable e%tends from the time it is d}_{om the time it is d}_eclared_eclared

until the time the script is

until the time the script is 8nished runnin#.8nished runnin#.

•

• _{At procedur}_{At procedur}_{e level, a variable e%ists only as}_{e level, a variable e%ists only as}_{lon# as you are in t}_{lon# as you are in the procedure}_{he procedure.}_.

•

• _{ou can have}_{ou can have local variables of the same}_{local variables of the same}_{name in several di=erent procedures}_{name in several di=erent procedures}

because each is

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•

• DimDim_varnameM_varnameM!!_MsubscriptsN_MsubscriptsN""_NM_NM## _varnameM_varnameM!!_MsubscriptsN_MsubscriptsN""_NN_NN $ $ $$ $ $

•

• >eclares variables and allocates stora#e space.>eclares variables and allocates stora#e space. •

• _{Variables declared with}_{Variables declared with} _Dim_Dim_{at the script level are available to all}_{at the script level are available to all}

procedures within the script.

•

• _{At the procedure level, variables are available only within the}_{At the procedure level, variables are available only within the}

procedure.

•

• _@_@_{ou can also}_{ou can also}_{use the}_{use the} _Dim_Dim_{statement with empty parentheses to}_{statement with empty parentheses to}

declare a dynamic array.

•

• _Note_Note _{When you use the}_{When you use the} _Dim_Dim_{statement in a procedure, you}_{statement in a procedure, you}

#enerally put the

#enerally put the DimDim statement at the be#innin# of the statement at the be#innin# of the

procedure.

(17)

•

• _Private_Private_varnameM_varnameM!_{!MsubscriptsN}_{MsubscriptsN"}_"NM_NM#_# _varnameM_varnameM!_{!MsubscriptsN}_{MsubscriptsN"}_"NN_NN _{$ $ $}_{$ $ $}

•

>eclares private variables and allocates stora#e space.

•

_{9rivate stateme}

_{nt variables are available only to the}

_{script in which}

they are declared.

•

_{The followin# e}

_{%ample illustrates u}

_{se of the}

_Private

_statement5

Private

Private "y4umber "y4umber ‘‘_{ 9rivate Variant variable.}_{ 9rivate Variant variable.}

Private

Private "yArray&-' "yArray&-' ‘‘_{ 9rivate array variable.}_{ 9rivate array variable.}

‘

‘_{ "ultiple 9rivate decl}_{ "ultiple 9rivate decl}_{arations of Variant variables.}_{arations of Variant variables.}

Private

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•

_Public

_varnameM

_!

_MsubscriptsN

_"

_NM

_#

_varnameM

_!

_MsubscriptsN

_"

_NN

_{$ $ $}

•

_{>eclares public variables and allocates stora#e space.}

•

Public

Public statement variables are available to all

_{statement variables are available to all procedur}

_procedur

_{es in}

all scripts.

•

@

ou can also use th

e

Public

statement with empty

parentheses to declare a dynamic array.

Public

Public "y4umber "y4umber ‘‘_{ 9ublic Variant variable.}_{ 9ublic Variant variable.}

Public

Public "yArray&-' "yArray&-' ‘‘_{ 9ublic array variable.}_{ 9ublic array variable.}

‘

‘_{ "ultiple 9ublic decl}_{ "ultiple 9ublic decl}_{arations of Variant variables.}_{arations of Variant variables.}

Public

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