OpenOffice.org BASIC Guide - OpenOffice.org wiki

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[First Name] = "Andrew" [DéjàVu] = 2 Working With Variables Implicit Variable Declaration Overview of a Basic Program Basic languages are designed to be easy to use. As a result, OpenOffice.org Basic enables the creation of a variable through simple usage and without an explicit declaration. In other words, a variable exists from the moment that you include it in your code. Depending on the variables that are already present, the following example declares up to three new variables: a = b + c Declaring variables implicitly is not good programming practice because it can result in the inadvertent introduction of a new variable through, for example, a typing error. Instead of producing an error message, the interpreter initializes the typing error as a new variable with a value of 0. It can be very difficult to locate errors of this kind in your code. Explicit Variable Declaration To prevent errors caused by an implicit declaration of variables, OpenOffice.org Basic provides a switch called: Option Explicit This must be listed in the first program line of each module and ensures that an error message is issued if one of the variables used is not declared. The Option Explicit switch should be included in all Basic modules. In its simplest form, the command for an explicit declaration of a variable is as follows: Dim MyVar This example declares a variable with the name MyVar and the type variant. A variant is a universal variable that can record all conceivable values, including strings, whole numbers, floating point figures, and Boolean values. Here are a few examples of Variant variables: MyVar = "Hello World" ' Assignment of a string MyVar = 1 ' Assignment of a whole number MyVar = 1.0 ' Assignment of a floating point number MyVar = True ' Assignment of a Boolean value The variables declared in the previous example can even be used for different variable types in the same program. Although this provides considerable flexibility, it is best to restrict a variable to one variable type. When OpenOffice.org Basic encounters an incorrectly defined variable type in a particular context, an error message is generated. Use the following style when you make a type-bound variable declaration: Dim MyVar As Integer ' Declaration of a variable of the integer type The variable is declared as an integer type and can record whole number values. You can also use the following style to declare an integer type variable: Dim MyVar% ' Declaration of a variable of the integer type The Dim instruction can record several variable declarations: Dim MyVar1, MyVar2 If you want to assign the variables to a permanent type, you must make separate assignments for each variable: Dim MyVar1 As Integer, MyVar2 As Integer If you do not declare the type for a variable, OpenOffice.org Basic assigns the variable a variant type. For Chapter 2 · The Language of OpenOffice.org BASIC 11
Working With Variables example, in the following variable declaration, MyVar1 becomes a variant and MyVar2 becomes an integer: Dim MyVar1, MyVar2 As Integer The following sections list the variable types that are available in OpenOffice.org Basic and describe how they can be used and declared. Strings Strings, together with numbers, form the most important basic types of OpenOffice.org Basic. A string consists of a sequence of consecutive individual characters. The computer saves the strings internally as a sequence of numbers where each number represents one specific character. From a Set of ASCII Characters to Unicode Character sets match characters in a string with a corresponding code (numbers and characters) in a table that describes how the computer is to display the string. The ASCII Character Set The ASCII character set is a set of codes that represent numbers, characters, and special symbols by one byte. The 0 to 127 ASCII codes correspond to the alphabet and to common symbols (such as periods, parentheses, and commas), as well as some special screen and printer control codes. The ASCII character set is commonly used as a standard format for transferring text data between computers. However, this character set does not include a range of special characters used in Europe, such as â, ä, and î, as well as other character formats, such as the Cyrillic alphabet. The ANSI Character Set Microsoft based its Windows product on the American National Standards Institute (ANSI) character set, which was gradually extended to include characters that are missing from the ASCII character set. Code Pages The ISO 8859 character sets provide an international standard. The first 128 characters of the ISO character set correspond to the ASCII character set. The ISO standard introduces new character sets (code pages) so that more languages can be correctly displayed. However, as a result, the same character value can represent different characters in different languages. Unicode Unicode increases the length of a character to four bytes and combines different character sets to create a standard to depict as many of the world's languages as possible. Version 2.0 of Unicode is now supported by many programs — including OpenOffice.org and OpenOffice.org Basic. String Variables OpenOffice.org Basic saves strings as string variables in Unicode. A string variable can store up to 65535 12 OpenOffice.org 3.2 BASIC Guide · March 2010
Page 1 and 2: OpenOffice.org 3.2 BASIC Guide
Page 3 and 4: 3 1 2 3 4 Contents Copyright.......
Page 5 and 6: Preface This guide provides an intr
Page 7 and 8: About OpenOffice.org Basic and allo
Page 9: Overview of a Basic Program In addi
Page 13 and 14: Numbers with long integer variables
Page 15 and 16: Numbers return incorrect values. Th
Page 17 and 18: Arrays Dim MyInteger(3) creates 4 i
Page 19 and 20: Scope and Life Span of Variables Sc
Page 21 and 22: Constants Const A = 10 You can also
Page 23 and 24: Branching B = 0 End If In this exam
Page 25 and 26: Loops use an explicit counter like
Page 27 and 28: Procedures and Functions ' ... here
Page 29 and 30: Procedures and Functions The exampl
Page 31 and 32: Error Handling The following code i
Page 33 and 34: Other Instructions End Sub & "Text:
Page 35 and 36: Conversion Functions calculates the
Page 37 and 38: Conversion Functions IsBoolean = Fa
Page 39 and 40: Strings Formatting Strings The Form
Page 41 and 42: Date and Time The Weekday function
Page 43 and 44: Files and Directories Note - VBA :
Page 45 and 46: Files and Directories The FreeFile
Page 47 and 48: Message and Input Boxes Display of
Page 49 and 50: Other Functions specifies the same
Page 51 and 52: Universal Network Objects (UNO) com
Page 53 and 54: Tools for Working with UNO The foll
Page 55 and 56: Overview of Central Interfaces basi
Page 57 and 58: 5 C H A P T E R 5 5 Working with
Page 59 and 60: XML File Format The StarDesktop Ope
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The StarDesktop The FileProperties
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The options of the print method The
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Doc = ThisComponent StyleFamilies =
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6 C H A P T E R 6 6 Text Documen
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described in Search and Replace. Th
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Paragraph Properties The Structure
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If TextElement.supportsService("com
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isEndOfSentence () returns True if
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Doc.Text.insertControlCharacter(Cur
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Dim Replace As Object Dim BritishWo
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More Than Just Text Note - Text tab
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Doc.Text.insertTextContent(Cursor,
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frame objects are set to the starti
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The following example shows how the
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7 C H A P T E R 7 7 Spreadsheet
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The same interface provides methods
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Cell = Sheet.getCellByPosition(0, 0
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StartColumn (long) first column in
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You can apply all of the named prop
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NumberFormatId = NumberFormats.addN
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ShadowFormat (struct) The Structure
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FooterBottomBorderDistance (long) d
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Definition of Elements to be Printe
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VARP variance based on the total po
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8 C H A P T E R 8 8 Drawings and
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Doc = ThisComponent Page = Doc.Draw
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RectangleShape.Position = Point Rec
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The lines are dark gray (Color) and
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service. Dim Doc As Object Dim Page
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An Overview of Various Drawing Obje
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Page.add(LineShape) Polypolygon Sha
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AdjustBlue (Short) blue value as a
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Point.x = 1000 Point.y = 1000 Size.
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Pause (long) the amount of time tha
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Using Charts in Spreadsheets The pr
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The Structure of Charts com.sun.sta
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The Structure of Charts Min (Double
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The Structure of Charts HasZAxisGri
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The Structure of Charts The followi
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10 C H A P T E R 1 0 10 Database
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User (String) user name Password (S
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Dim Statement As Object Dim ResultS
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FORWARD_ONLY ResultSet only permits
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11 C H A P T E R 1 1 11 Dialogs
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Closing With the Close Button in th
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Multi-Page Dialogs Properties A dia
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Control element-specific events: Ev
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Buttons (short) X (long) Y (long) b
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Temporary (Boolean) the focus is te
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Model.Label (String) label that is
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Model.HScroll (Boolean) the text ha
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12 C H A P T E R 1 2 12 Forms In
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Accessing the View of Control Eleme
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Tag (String) Control Element Forms
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Enabled (Boolean) the control eleme
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LineCount (Short) number of lines o
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