Object Variables Visual Basic for Applications 3.

Object Variables

Visual Basic for Applications

3

Objectives

In this tutorial, you will learn how to: Explain how properties and variables are stored in

memory

Create an object variable using the Dim statement

Select the appropriate name and data type for an object variable

Use the Set statement to assign an object’s address to an object variable

Insert a row, value, and formula into an Excel worksheet using VBA code

3

Objectives

In this tutorial, you will learn how to: Format an Excel worksheet using VBA Code Assign a theme to a Word document using

VBA code Create a hyperlink in a Word document using

VBA code Open an Access report using VBA code Order the records in an Access report using

VBA code

3

Concept Lesson:Memory Cells

Every object in a VBA-enabled application has a set of properties whose values control the object’s appearance and behavior

VBA stores each property, along with its corresponding value, inside the computer in an area called internal memory

When VBA creates an object, it reserves a group of boxes (memory cells) in which it stores information about the object

3

Illustration of Memory Cells that Store Property Values

3

How Each Object Occupies a Separate Section in Memory

3

Memory Cells

In addition to assigning both a name and a value to each property’s memory cell, VBA also assigns a data type

The data type refers to the type of data the memory cell can store

You can determine the type of data that a property's memory cell can store by viewing the property’s Help screen

3

Variables

A programmer also can reserve memory cells

for storing information

The memory cells reserved by the

programmer are called variables

Like all reserved memory cells, the variables

that you create must have both a name and a

data type

3

Variables

Numeric variables, for example, can store only numbers, while String variables can store numbers, letters, and special characters, such as the dollar sign ($)

Programmers use object variables to make procedures easier to write and understand

Object variables also help to improve the performance of a procedure by allowing the procedure to run more quickly

3

Object Variables3

An object variable is a memory cell (box) that contains the address of an object in memory

The address tells VBA where the object is located The address contained in an object variable

“points” to the location of an object in memory When VBA processes the MsgBox Prompt:

=Application.Presentations(1).Slides(1).Name instruction, first it must locate the appropriate Application object in memory, then it must locate the first Presentation object within the Presentations collection, followed by the first Slide object within the Slides collection

An Object Variable and the Object to Which It Refers

3

Instructions to Display the First Slide Object’s Name

and Layout Properties

3

Object Variables

VBA repeats this process when it executes the MsgBox Prompt:=Application.Presentations(1) .Slides(1).Layout instruction—once again having to locate the appropriate Application, Presentation, and Slide objects in memory

If you assign the Slide object’s address to an object variable named sldFirst, you can use the last two instructions shown in Figure 3-4 to display the Slide object’s Name and Layout properties

3

Object Variables3

The sldFirst object variable contains an address that points directly to the location of the Slide object in memory

A variable’s scope refers to which procedures in the project can use the variable

Variables in VBA can have one of three scopes:– Procedure-level

– Module-level

– Public

Reserving a Procedure-Level Variable

A procedure-level variable is reserved, or declared, within a procedure, and it can be used only by the procedure in which it is declared

You use the VBA Dim statement to reserve a procedure-level variable

The syntax of the Dim statement is Dim variablename As datatype, where variablename represents the name of the variable (memory cell) and datatype represents its data type

When VBA processes the Dim statement in a procedure, it reserves a memory cell to which it assigns variablename as the name and datatype as the data type

3

Selecting the Appropriate Data Type and Name for an

Object Variable

3

You must assign a data type to each of the variables (memory cells) that you reserve

If an object variable will point to a Document object, then the object variable’s data type willbe Document

If an object variable will contain the address of a Worksheet object, then the object variable’s data type will be Worksheet

In addition to assigning a data type to a variable, you also must assign a name to the variable

The name should help you remember both the data type and purpose of the variable

Data Types Corresponding to Some of the Objects Available

in the Microsoft Office Applications

3

Data Types and Their Three-Character IDs

3

Selecting the Appropriate Data Type and Name for an

Object Variable It is a common practice to type the three-

character ID in lowercase and capitalize thefirst letter in the part of the name that identifies the purpose

In addition to being descriptive, the name that a programmer assigns to a variable must follow several specific rules

When you use the Dim statement to declare an object variable, VBA reserves a memory cell to which it attaches variablename as the name and datatype as the data type

3

Rules and Examples for Variable Names

3

Selecting the Appropriate Data Type and Name for an

Object Variable

3

VBA also automatically stores the keyword Nothing in the object variable, which is referred to as initializing the variable

Using the Set Statement

You use the Set statement to assign the address of an object to an object variable

The syntax of the Set statement is Set objectVariableName=object, where objectVariableName is the name of an object variable, and object is the object whose address you want to store in the variable

The Set statement locates the object in memory and then stores the object’s address in the memory cell whose name is objectVariableName

3

Examples of the Set Statement3

Summary

To create a procedure-level object variable, and then assign an address to it:

Use the Dim statement to create the variable

For a listing of data types corresponding to some of the objects available in the Microsoft Office applications refer to Figure 3-5

Use the Set statement to assign the address of an object to an object variable

3

Excel Lesson:Creating the FormatWorksheet

Macro Procedure To open

Martin’s workbook, and then insert a module and a procedure, use the steps on pages 168 to 170 of the textbook

3

Add Procedure Dialog Box3

Worksheet Format Desired by the District Sales Manager

3

Worksheet Format Desired by the Regional Sales Manager

3

Creating the FormatWorksheet Macro Procedure

3

Pseudocode, which is composed of short English statements, isa tool programmers use to help them plan the steps that a procedure must take in order to perform an assigned task

Inserting Rows Into a Worksheet

You insert a row into a worksheet using the syntax worksheetObject.Rows(rowNumber).Insert, where worksheetObject is the name of a Worksheet object and rowNumber is the number of rows above which the new row will be inserted

3

Inserting Rows Into a Worksheet

To create an object variable and then use it to enter instructions, use the steps on pages 174 and 175 of the textbook

3

Entering a Value Into aRange Object

A row, a column, or a group of contiguous or

noncontiguous cells in a worksheet also are

Excel Range objects

To enter the instruction that will assign

“Paradise Electronics” to cell A1, use

the steps on pages 175 and 176 of

the textbook

3

Entering a Formula Into a Range Object

3

You need to enter the following formulas in cells B13 through D13 in the worksheet:B13 formula = SUM (B4:B12)

C13 formula = SUM (C4:C12)

D13 formula = SUM (D4:D12) These formulas will add the contents of their respective columns

Formatting a Range Object

A collection of predesigned worksheet formats is availablein Excel

To view a complete listing of the Excel predesigned formats, display the AutoFormat method’s Help screen

To enter the instruction that formats the worksheet, use thesteps on page 178 of the textbook

3

Current Status of the FormatWorksheet Procedure

3

Previewing and Printing a Worksheet Object

To complete the FormatWorksheet procedure, then save and run the procedure, use the steps listed on pages 179 to 181 of the textbook

3

First Quarter WorksheetAfter Running the

FormatWorksheet Macro

3

Word Lesson:Creating the FormatPromo

Macro Procedure Begin by opening Pat’s document, which is

located in the Tut03\Word folder on yourData Disk

To open Pat’s document, and then insert a module and a procedure, use the steps on pages 184 to 186 in the textbook

A theme in Microsoft Word is a set of unified design elements and color schemes for background images, bullets, fonts, horizontal lines, and other document elements

3

Promo Document3

Add Procedure Dialog Box3

Example of a Formatted Document

3

Pseudocode for theFormatPromo Procedure

3

Partial Listing of Themes Availablein Microsoft Word

3

Applying a Theme to a Document

You use the ApplyTheme method to apply a theme to a document

The syntax of the ApplyTheme method is documentObject.ApplyThemeName:=themeName, where documentObject is the name of a Document object and themeName is the nameof a theme

To create an object variable named docPromo and then use it in the ApplyTheme instruction, use the steps on page 189 of the textbook

3

Changing the Document’s Font Size

You use the following syntax to change the size of the font used in the document: documentObject.Content.Font.Size=font Size

To change the document’s font size to 14 points:

1. Type ’change document’s font size and press the Enter key

2. Type docpromo.content.font.size=14 and press the Enter key

3

Adding a Hyperlink to a Document

3

You use the Add method of the Document object’s Hyperlinks collection to add a hyperlink to a document

The syntax of the Add method is documentObject.Hyperlinks.Add Anchor:=rangeObject, Address:=linkAddress

To convert the club’s name to a hyperlink, use the steps on pages 190 to 192 of the textbook

Completed FormatPromo Procedure3

Promo Document After Running the FormatPromo Macro

3

Access Lesson:Creating the

DisplayByGrade Procedure Begin by opening Professor Martinez’s

database, which is located in the Tut03\Access folder on your Data Disk

Then view the StudentReport

To open Professor Martinez’s database, then view the StudentReport report, use the steps on pages 195 and 196 of the textbook

To begin creating the DisplayByGrade procedure, use the steps on pages 196 and 197 of the textbook

3

Maximized StudentReport Report3

Creating the DisplayByGrade Procedure

3

Opening an Access Report

You use the OpenReport method of the DoCmd object to open an Access report

The syntax of the OpenReport method is DoCmd.OpenReport Reportname:=reportName, View:=viewName, where reportName is the name of a report and viewName is the name of a view

To create an object variable named rptStudent and then assign the StudentReport object’s address to it, use the steps on pages 199 and 200 of the textbook

3

Valid View Names for the OpenReport Method’s

View Argument

3

Ordering the Records in a Report

To change the order of the records that appear in a report, you need first to set the Report object’s OrderByOn property to the Boolean value True

To complete the DisplayByGrade procedure, use the steps on pages 200 and 201 of the textbook

3

Creating theDisplayByGradeMacro Macro

3

You use the Macro window to create an Access macro

The macro then can be run from eitherthe Macro window or the Database window in Access

To create the DisplayByGradeMacro macro, and then save and run the macro, use the steps on pages 201 to 203 of the textbook

Macro Window Showingthe Completed

DisplayByGradeMacro Macro

3

StudentReport Report in Grade Order

3