book

VBScript in a Nutshell, 2nd Edition

by Paul Lomax, Matt Childs, Ron Petrusha

March 2003

Intermediate to advanced

512 pages

14h 30m

English

O'Reilly Media, Inc.

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Foreword
Preface
Why This Book?Who Should Read This Book?How This Book Should Be UsedIf You’re New to VBScriptIf You’re a VBScript ProgrammerIf You’re a VB or VBA Developer New to VBScriptHow This Book Is StructuredThe Format of the Language ReferenceConventions in This BookHow To Contact UsAcknowledgments
I. The Basics
1. Introduction
1.1. VBScript’s History and Uses1.2. What VBScript Is Used For: Gluing Together Objects1.2.1. Properties1.2.2. Methods1.2.3. Events1.3. Differences Between VBScript and VBA
2. Program Structure
2.1. Functions and Procedures2.1.1. Defining Subroutines: The Sub . . . End Sub Construct2.1.2. Calling a Subroutine2.1.3. Defining Functions: The Function . . . End Function Construct2.1.4. Passing Variables into a Subroutine2.1.5. Exiting a Routine with the Exit Statement2.2. Classes2.2.1. The Class Construct2.2.2. Class Variables2.2.3. Class Properties2.2.4. Class Methods2.2.5. Class Events2.3. Global Code2.3.1. Active Server Pages2.3.2. Windows Script Host2.3.3. Client-Side Scripts for Internet Explorer2.3.4. Outlook Forms2.4. Reusable Code Libraries2.4.1. Active Server Pages2.4.2. Windows Script Host2.4.3. Client-Side Scripts for Internet Explorer
3. Data Types and Variables
3.1. VBScript Data Types: The Many Faces of the Variant3.1.1. Variant Data Types3.1.2. Determining the Variant Type3.1.2.1. VarType3.1.2.2. TypeName3.1.3. Converting from One Data Type to Another3.2. Variables and Constants3.2.1. What Is a Variable?3.2.2. What Is a Constant?3.2.3. Intrinsic Constants3.2.4. Constants in Type Libraries3.2.5. Declaring Variables and Constants3.2.5.1. Option Explicit3.2.6. Array Variables3.2.6.1. Fixed arrays3.2.6.2. Dynamic arrays3.2.6.3. Determining array boundaries: UBound and LBound3.2.6.4. Multidimensional arrays3.2.6.5. Dynamic multidimensional arrays3.2.6.6. Using UBound with multidimensional arrays3.2.7. Scope and Visibility3.2.7.1. Global scope3.2.7.2. Local scope3.2.7.3. Public visibility3.2.7.4. Private
4. Error Handling and Debugging
4.1. Debugging4.1.1. Syntax Errors4.1.1.1. Syntax errors at compile time4.1.1.2. Syntax errors at runtime4.1.2. Logical Errors4.1.2.1. Logical errors that affect program results4.1.2.2. Logical errors that generate error messages4.1.3. The Microsoft Script Debugger4.1.3.1. Launching the Script Debugger4.1.3.2. The Script Debugger interface4.1.3.3. Tracing execution with the Script Debugger4.1.3.4. Determining the value of a variable, expression, or function at runtime4.1.3.5. Changing variable values at runtime4.2. Error Handling4.2.1. The On Error Resume Next Statement4.2.2. The Err Object4.2.2.1. Err object properties4.2.2.2. Err object methods4.3. Common Problem Areas and How to Avoid Them
5. VBScript with Active Server Pages
5.1. How ASP Works5.1.1. The global.asa File5.1.2. Including Server-Side Script in Web Pages5.2. Active Server Pages Object Model
6. Programming Outlook Forms
6.1. Why Program Outlook Forms?6.2. The Form-Based Development Environment6.2.1. Interfaces and Objects6.2.2. Outlook Form Design Mode6.2.3. The VBScript Environment6.3. Running Your Code6.4. Program Flow6.5. The Outlook Object Model6.5.1. The Current Item6.5.2. The Inspector Object6.5.3. The Pages Collection6.5.4. The FormDescription Object6.5.5. The NameSpace Object6.5.6. The MAPIFolder Object6.5.7. Outlook Constants6.6. Accessing Other Object Models
7. Windows Script Host 5.6
7.1. Why Use WSH?7.2. Running WSH Scripts7.3. Program Flow7.3.1. Simple Script Files7.3.2. Script Files with XML Code7.4. The WSH Object Model7.4.1. The WScript Object7.4.2. The WshArguments Object7.4.3. The WshController Object7.4.4. The WshEnvironment Object7.4.5. The WshNamed Object7.4.6. The WshNetwork Object7.4.7. The WshRemote Object7.4.8. The WshRemoteError Object7.4.9. The WshScriptExec Object7.4.10. The WshShell Object7.4.11. The WshShortcut Object7.4.12. The WshSpecialFolders Object7.4.13. The WshUnnamed Object7.4.14. The WshUrlShortcut Object7.5. WSH Language Elements7.6. Accessing Other Object Models

8. VBScript with Internet Explorer
8.1. The <SCRIPT> Tag8.1.1. <SCRIPT> Attributes8.1.1.1. The LANGUAGE attribute8.1.1.2. The SRC attribute8.1.1.3. The FOR attribute8.1.2. Where to Place the <SCRIPT> Tag8.1.3. Using <!——> with <SCRIPT>8.2. What Can You Do with Client-Side Scripting?8.2.1. Interacting with the Client8.2.2. Handling Events8.2.3. Data Validation8.3. Understanding the IE Object Model8.3.1. The Window Object8.3.2. The Document Object8.3.3. The Elements Collection and HTML Intrinsic Controls8.3.3.1. The textbox control8.3.3.2. The checkbox control8.3.3.3. The radio button control8.3.3.4. The list box8.3.3.5. Command button controls8.3.4. The History Object8.3.5. The Event Object8.3.6. Using the Document Object Model
9. Windows Script Components
9.1. The Script Component Wizard9.2. Writing Component Code9.3. Using the Component9.3.1. Registration9.3.2. Instantiating the Component9.4. WSC Programming Topics9.4.1. Handling Events9.4.2. Using an Interface Handler: ASP9.4.3. Using Resources9.4.4. Building an Object Model
II. Reference
10. The Language Reference
Abs Function
Array Function
Asc, AscB, AscW Functions
Atn Function
Call Statement
CBool Function
CByte Function
CCur Function
CDate Function
CDbl Function
Chr, ChrB, ChrW Functions
CInt Function
Class Statement
CLng Function
Const Statement
Cos Function
CreateObject Function
CSng Function
CStr Function
Date Function
DateAdd Function
DateDiff Function
DatePart Function
DateSerial Function
DateValue Function
Day Function
Dictionary Object
Dictionary.Add Method
Dictionary.CompareMode Property
Dictionary.Count Property
Dictionary.Exists Method
Dictionary.Item Property
Dictionary.Items Method
Dictionary.Key Property
Dictionary.Keys Method
Dictionary.Remove Method
Dictionary.RemoveAll Method
Dim Statement
Do . . . Loop Statement
Drive Object
Drives Collection Object
End . . . Statement
Erase Statement
Err Object
Err.Clear Method
Err.Description Property
Err.HelpContext Property
Err.HelpFile Property
Err.Number Property
Err.Raise Method
Err.Source Property
Escape Function
Eval Function
Execute Statement
ExecuteGlobal Statement
Exit Statement
Exp Function
File Object
File.Copy Method
File.Delete Method
File.Move Method
File.OpenAsTextStream Method
File System Object Model
Files Collection Object
FileSystemObject Object
FileSystemObject.BuildPath Method
FileSystemObject.CopyFile Method
FileSystemObject.CopyFolder Method
FileSystemObject.CreateFolder Method
FileSystemObject.CreateTextFile Method
FileSystemObject.DeleteFile Method
FileSystemObject.DeleteFolder Method
FileSystemObject.DriveExists Method
FileSystemObject.Drives Property
FileSystemObject.FileExists Method
FileSystemObject.FolderExists Method
FileSystemObject.GetAbsolutePathName Method
FileSystemObject.GetBaseName Method
FileSystemObject.GetDrive Method
FileSystemObject.GetDriveName Method
FileSystemObject.GetExtensionName Method
FileSystemObject.GetFile Method
FileSystemObject.GetFileName Method
FileSystemObject.GetFileVersion Method
FileSystemObject.GetFolder Method
FileSystemObject.GetParentFolderName Method
FileSystemObject.GetSpecialFolder Method
FileSystemObject.GetStandardStream Method
FileSystemObject.GetTempName Method
FileSystemObject.MoveFile Method
FileSystemObject.MoveFolder Method
FileSystemObject.OpenTextFile Method
Filter Function
Fix Function
Folder Object
Folder.Copy Method
Folder.CreateTextFile Method
Folder.Delete Method
Folder.Move Method
Folders Collection Object
Folders.Add Method
For . . . Next Statement
For Each . . . Next Statement
FormatCurrency, FormatNumber, FormatPercent Functions
FormatDateTime Function
Function Statement
GetLocale Function
GetObject Function
GetRef Function
Hex Function
Hour Function
If . . . Then . . . Else Statement
Initialize Event
InputBox Function
InStr, InStrB Functions
InstrRev Function
Int Function
Is Operator
IsArray Function
IsDate Function
IsEmpty Function
IsNull Function
IsNumeric Function
IsObject Function
Join Function
LBound Function
LCase Function
Left, LeftB Functions
Len, LenB Functions
LoadPicture Function
Log Function
LTrim Function
Match Object
Matches Collection Object
Me Keyword
Mid, MidB Functions
Minute Function
Month Function
MonthName Function
MsgBox Function
Now Function
Oct Function
On Error Statement
Option Explicit Statement
Private Statement
Property Get Statement
Property Let Statement
Property Set Statement
Public Statement
Randomize Sub
ReDim Statement
RegExp Object
RegExp.Execute Method
RegExp.Global Property
RegExp.IgnoreCase Property
RegExp.Pattern Property
RegExp.Replace Method
RegExp.Test Method
Rem Statement
Replace Function
RGB Function
Right, RightB Functions
Rnd Function
Round Function
RTrim Function
ScriptEngine Function
ScriptEngineBuildVersion Function
ScriptEngineMajorVersion Function
ScriptEngineMinorVersion Function
Second Function
Select Case Statement
SetLocale Function
Set Statement
Sgn Function
Sin Function
Space Function
Split Function
Sqr Function
StrComp Function
String Function
StrReverse Function
Sub Statement
Tan Function
Terminate Event
TextStream Object
TextStream.Close Method
TextStream.Read Method
TextStream.ReadAll Method
TextStream.ReadLine Method
TextStream.Skip Method
TextStream.SkipLine Method
TextStream.Write Method
TextStream.WriteBlankLines Method
TextStream.WriteLine Method
Time Function
Timer Function
TimeSerial Function
TimeValue Function
Trim Function
TypeName Function
UBound Function
UCase Function
Unescape function
VarType Function
Weekday Function
WeekdayName Function
While . . . Wend Statement
With Statement
Year Function
III. Appendixes
A. Language Elements by Category
A.1. Array HandlingA.2. AssignmentA.3. CommentA.4. ConstantsA.5. Data Type ConversionA.6. Date and TimeA.7. Dictionary ObjectA.8. Error HandlingA.9. File System ObjectsA.9.1. Drive ObjectA.9.2. Drives Collection ObjectA.9.3. File ObjectA.9.4. Files Collection ObjectA.9.5. FileSystemObject ObjectA.9.6. Folder ObjectA.9.7. Folders Collection ObjectA.9.8. TextStreamObjectA.10. Information FunctionsA.11. Mathematical and NumericA.12. MiscellaneousA.13. Object ProgrammingA.14. Program Structure and FlowA.15. String ManipulationA.16. User InteractionA.17. Variable Declaration
B. VBScript Constants
B.1. Color ConstantsB.2. Comparison ConstantsB.3. Date and Time ConstantsB.4. Date Format ConstantsB.5. Error ConstantB.6. Logical and TriState ConstantsB.7. Message Box ConstantsB.8. String ConstantsB.9. Variable Type Constants
C. Operators
C.1. Arithmetic OperatorsC.2. String OperatorC.3. Comparison OperatorsC.3.1. The Is OperatorC.4. Logical and Bitwise OperatorsC.5. Operator Precedence
D. Locale IDs
E. The Script Encoder
E.1. How Encoding and Decoding WorksE.2. Script Encoder SyntaxE.3. Encoding ExamplesE.3.1. Encoding .vbs FilesE.3.2. Encoding .wsf FilesE.3.3. Encoding ASP Files with Client-Side Script
About the Authors
Colophon
Copyright

Content preview from VBScript in a Nutshell, 2nd Edition

Name

Erase Statement

Syntax

Erase arraylist

arraylist

Use: Required

Data Type: Variant array

A list of array variables to clear.

Description

Resets the elements of an array to their initial (unassigned) values. In short, Erase “clears out” or empties an array.

Rules at a Glance

Specify more than one array to be erased by using commas to delimit arraylist.
Fixed array variables remain dimensioned; on the other hand, all memory allocated to dynamic arrays is released.
After the Erase statement executes, TypeName returns “Variant( )” for a fixed-length array; in addition, the IsEmpty function returns True when individual members of the array are passed to it, and comparisons of an individual member of the array with an empty string ("") and with zero both return True. On the other hand, the TypeName function returns Empty for a dynamic array, and comparisons of the array with an empty string ("") and zero also return True.

Programming Tips and Gotchas

Once you use Erase to clear dynamic arrays, they must be redimensioned with ReDim before being used again. This is because Erase releases the memory storage used by the dynamic array back to the operating system, which sets the array to have no elements.

VBA/VBScript Differences

Because VBA can be strongly typed, the behavior of the Erase statement in clearing a fixed array varies, depending on the array’s data type. The effect of the Erase statement on a fixed variant array in VBScript is described earlier in the “Rules at Glance” section.