Visual Basic Ebook Full English

Contents in Brief Preface xvii Chapter 1 Introduction to Programming and Visual Basic 1 Chapter 2 Creating Applications with Visual Basic 43 Chapter 7 Multiple Forms, Modules, and Menus

Visual Basic ®

2012

S i x t h E d i t i o n

Visual Basic ®

2012

S i x t h E d i t i o n

Tony Gaddis Haywood Community College

Kip Irvine Florida International University

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Library of Congress Cataloging-in-Publication Data available upon request.

10 9 8 7 6 5 4 3 2 1

ISBN 10: 0-13-312808-3 ISBN 13: 978-0-13-312808-6

Contents in Brief

Preface xvii

Chapter 1 Introduction to Programming and Visual Basic 1

Chapter 2 Creating Applications with Visual Basic 43

Chapter 7 Multiple Forms, Modules, and Menus 403

Chapter 9 Files, Printing, and Structures 541

Chapter 12 Classes, Collections, and Inheritance 733

Appendix A Advanced User Interface Controls and Techniques 795

Appendix B Windows Presentation Foundation (WPF) 809

Appendix C Converting Mathematical Expressions

Contents

Preface xvii Chapter 1 Introduction to Programming and Visual Basic 1

1.1 Computer Systems: Hardware and Software 2

1.2 Programs and Programming Languages 4

TUTORIAL 1-1: Running the Wage Calculator application 8

TUTORIAL 1-2: Running an application that demonstrates event handlers 11

1.3 More about Controls and Programming 11

TUTORIAL 1-3: Running an application that demonstrates various controls 12

1.4 The Programming Process 16

1.5 Visual Studio and Visual Studio Express (the Visual Basic Environment) 20

TUTORIAL 1-4: Starting Visual Studio and setting up the environment 21

TUTORIAL 1-5: Starting a new Visual Basic project 25

TUTORIAL 1-6: Becoming familiar with the Visual Studio environment 34

Summary 36 • Key Terms 37 • Review Questions and Exercises 37 • Programming Challenges 41 Chapter 2 Creating Applications with Visual Basic 43 2.1 Focus on Problem Solving: Building the Directions Application 43

TUTORIAL 2-1: Beginning the Directions application 46

TUTORIAL 2-2: Adding a Label control to the Directions application 48

TUTORIAL 2-3: Changing the Label’s font size and style 50

TUTORIAL 2-4: Deleting a control 52

TUTORIAL 2-5: Inserting a PictureBox control 53

TUTORIAL 2-6: Running the application 57

TUTORIAL 2-7: Opening an existing project and becoming familiar with the Properties window 62

2.2 Focus on Problem Solving: Responding to Events 63

TUTORIAL 2-8: Adding a Label control for the written directions 64

TUTORIAL 2-9: Adding the Display Directions button and its Click event handler 68

TUTORIAL 2-10: Adding the Exit button and its Click event handler 76

TUTORIAL 2-11: Adding comments to the Directions project code 79

TUTORIAL 2-12: Changing the text colors 81

TUTORIAL 2-13: Setting the FormBorderStyle property and locking the controls in the Directions application 83

2.3 Modifying a Control’s Text Property with Code 85

TUTORIAL 2-14: Examining an application that displays messages in a Label control 86

2.4 The AutoSize, BorderStyle, and TextAlign Properties 88

2.5 Displaying User Messages 90

TUTORIAL 2-15: Displaying message boxes 91

2.6 Clickable Images 95

TUTORIAL 2-16: Writing Click event handlers for PictureBox controls 95

2.7 Using Visual Studio Help 97

2.8 Debugging Your Application 99

TUTORIAL 2-17: Locating a compile error in design mode 100

Summary 102 • Key Terms 103 • Review Questions and Exercises 104 • Programming Challenges 106 Chapter 3 Variables and Calculations 111 3.1 Gathering Text Input 111

TUTORIAL 3-1: Using a TextBox control 112

TUTORIAL 3-2: Building the Date String application 115

TUTORIAL 3-3: Using the Focusmethod 118

TUTORIAL 3-4: Changing the tab order 119

TUTORIAL 3-5: Setting access keys, accept, and cancel buttons 123

3.2 Variables and Data Types 124

TUTORIAL 3-6: Assigning text to a variable 131

3.3 Performing Calculations 136

3.4 Mixing Different Data Types 143

TUTORIAL 3-7: Examining a Simple Calculator application 151

3.5 Formatting Numbers and Dates 154

TUTORIAL 3-8: Examining the Format Demo application 157

3.6 Class-Level Variables 159

3.7 Exception Handling 160

TUTORIAL 3-9: Exception Demonstration 161

TUTORIAL 3-10: Salary Calculator project with exception handling 164

3.8 Group Boxes 170

3.9 The Load Event 173

3.10 Focus on Program Design and Problem Solving: Building the Room Charge Calculator Application 173

TUTORIAL 3-11: Beginning the Room Charge Calculator application 179

TUTORIAL 3-12: Changing a label’s colors 184

3.11 More about Debugging: Locating Logic Errors 186

TUTORIAL 3-13: Single-stepping through an application’s code at runtime 186

Summary 192 • Key Terms 195 • Review Questions and Exercises 196 • Programming Challenges 202 Chapter 4 Making Decisions 209 4.1 The Decision Structure 209

4.2 The If Then Statement 211

TUTORIAL 4-1: Examining an application that uses the If Then statement 214

4.3 The If Then Else Statement 217

TUTORIAL 4-2: Completing an application that uses the If Then Else statement 218

4.4 The If Then ElseIf Statement 220

TUTORIAL 4-3: Completing an application that uses

the If Then ElseIf statement 221

4.5 Nested If Statements 227

TUTORIAL 4-4: Completing an application with a nested If statement 227

4.6 Logical Operators 229

4.7 Comparing, Testing, and Working with Strings 235

TUTORIAL 4-5: Examining an application that performs string comparisons 238

TUTORIAL 4-6: Completing a string searching application 243

4.8 The Select Case Statement 246

TUTORIAL 4-7: Examining Crazy Al’s Sales Commission Calculator application 249

4.9 Introduction to Input Validation 252

TUTORIAL 4-8: Examining an application that uses TryParse for input validation 254

4.10 Focus on GUI Design: Radio Buttons and Check Boxes 257

TUTORIAL 4-9: Completing an application with radio buttons and check boxes 259

4.11 Focus on Program Design and Problem Solving: Building the Health Club Membership Fee Calculator Application 260

TUTORIAL 4-10: Building the Health Club Membership Fee Calculator application 266

Summary 270 • Key Terms 271 • Review Questions and Exercises 272 • Programming Challenges 277 Chapter 5 Lists and Loops 285 5.1 Input Boxes 285

5.2 List Boxes 287

TUTORIAL 5-1: Creating list boxes 292

5.3 Introduction to Loops: The Do While Loop 296

TUTORIAL 5-2: Completing an application that uses the Do While loop 297

TUTORIAL 5-3: Modifying the Do While Demo application to use a posttest loop 301

TUTORIAL 5-4: Using a loop to keep a running total 303

TUTORIAL 5-5: Examining an application that uses a user-controlled loop 305

5.4 The Do Until and For Next Loops 307

TUTORIAL 5-6: Examining an application that uses the Do Until loop 308

TUTORIAL 5-7: Examining an application that uses the For Next loop 312

TUTORIAL 5-8: Completing an application that uses the For Next loop 313

5.5 Nested Loops 317

5.6 Multicolumn List Boxes, Checked List Boxes, and Combo Boxes 318

TUTORIAL 5-9: Creating combo boxes 322

5.7 Random Numbers 324

TUTORIAL 5-10: Creating the Coin Toss application 326

5.8 Simplifying Code with the With End With Statement 328

5.9 ToolTips 329

TUTORIAL 5-11: Adding ToolTips to an application 330

5.10 Focus on Program Design and Problem Solving: Building the Vehicle Loan Calculator Application 331

TUTORIAL 5-12: Building the Vehicle Loan Calculator application 334

Summary 339 • Key Terms 340 • Review Questions and Exercises 340 • Programming Challenges 346 Chapter 6 Procedures and Functions 355 6.1 Procedures 356

TUTORIAL 6-1: Examining an application with a procedure 356

TUTORIAL 6-2: Creating and calling procedures 359

6.2 Passing Arguments to Procedures 363

TUTORIAL 6-3: Examining an application that demonstrates passing an argument to a procedure 365

TUTORIAL 6-4: Working with ByVal and ByRef 368

6.3 Functions 371

TUTORIAL 6-5: Sale Price Calculator application 372

6.4 More about Debugging: Stepping Into, Over, and Out of Procedures and Functions 379

TUTORIAL 6-6: Practicing the Step Into command 380

TUTORIAL 6-7: Practicing the Step Over command 381

TUTORIAL 6-8: Practicing the Step Out command 381

6.5 Focus on Program Design and Problem Solving: Building the Bagel and Coffee Price Calculator Application 383

TUTORIAL 6-9: Building the Bagel House application 388

Summary 392 • Key Terms 392 • Review Questions and Exercises 393 • Programming Challenges 396 Chapter 7 Multiple Forms, Modules, and Menus 403 7.1 Multiple Forms 403

TUTORIAL 7-1: Creating an application with two forms 411

TUTORIAL 7-2: Completing an application that displays modal and modeless forms 414

TUTORIAL 7-3: Accessing a control on a different form 420

7.2 Modules 425

TUTORIAL 7-4: Examining an application that uses a module 428

7.3 Menus 435

TUTORIAL 7-5: Building a menu 442

7.4 Focus on Problem Solving: Building the High Adventure Travel Agency Price Quote Application 447

TUTORIAL 7-6: Building the High Adventure Travel Agency Price Quote application 449

Summary 455 • Key Terms 456 • Review Questions and Exercises 456 • Programming Challenges 461 Chapter 8 Arrays and More 469 8.1 Arrays 469

TUTORIAL 8-1: Using an array to hold a list of random lottery numbers 474

TUTORIAL 8-2: Using an array to hold a list of names entered by the user 477

TUTORIAL 8-3: Completing an application that uses array elements

in a calculation 480

8.2 Array Processing Techniques 484

TUTORIAL 8-4: Using parallel arrays 488

8.3 Procedures and Functions That Work with Arrays 494

TUTORIAL 8-5: Examining an application that passes an array to procedures and functions 496

8.4 Multidimensional Arrays 501

TUTORIAL 8-6: Completing the Seating Chart application 505

8.5 Focus on GUI Design: The Enabled Property and the Timer Control 510

TUTORIAL 8-7: The Timer Demo 511

TUTORIAL 8-8: Creating the Catch Me game 512

8.6 Focus on GUI Design: Anchoring and Docking Controls 515

8.7 Focus on Problem Solving: Building the Demetris Leadership Center Application 518

TUTORIAL 8-9: Building the Demetris Leadership Center Sales Reporting application 521

8.8 Using Lists to Hold Information (Optional Topic) 524

TUTORIAL 8-10: Building a List from User Input 526

Summary 529 • Key Terms 530 • Review Questions and Exercises 531 • Programming Challenges 536 Chapter 9 Files, Printing, and Structures 541 9.1 Using Files 541

TUTORIAL 9-1: Completing an application that writes data to a file 546

TUTORIAL 9-2: Completing an application that reads a file 551

TUTORIAL 9-3: Examining an application that detects the end of a file 555

9.2 The OpenFileDialog, SaveFileDialog, FontDialog, and ColorDialog Controls 561

TUTORIAL 9-4: Creating a Simple Text Editor application 565

9.3 The PrintDocument Control 574

TUTORIAL 9-5: Adding printing capabilities to the Simple Text Editor application 575

9.4 Structures 580

TUTORIAL 9-6: Examining an application with a structure 583

Summary 585 • Key Terms 585 • Review Questions and Exercises 586 • Programming Challenges 592 Chapter 10 Working with Databases 597 10.1 Database Management Systems 597

10.2 Database Concepts 598

10.3 DataGridView Control 602

TUTORIAL 10-1: Showing a database table in a DataGridView control 603

TUTORIAL 10-2: Sorting and updating the SalesStaff table 611

10.4 Data-Bound Controls 614

TUTORIAL 10-3: Binding a DataGridView to the SalesStaff table 619

TUTORIAL 10-4: Binding individual controls to the SalesStaff table 621

TUTORIAL 10-5: Displaying the Karate Members table in a ListBox Control 625

TUTORIAL 10-6: Inserting Karate member payments 628

TUTORIAL 10-7: Adding a total to the Insert Karate Payments application 632

10.5 Structured Query Language (SQL) 633

TUTORIAL 10-8: Filtering rows in the SalesStaff table 641

10.6 Focus on Problem Solving: Karate School Management Application 643

TUTORIAL 10-9: Creating the Karate School Manager startup form 647

TUTORIAL 10-10: Adding the Membership / List All function to the Karate School Manager 647

TUTORIAL 10-11: Adding the Membership / Add New Member function to the Karate School Manager 650

TUTORIAL 10-12: Adding the Membership / Find Member function to the Karate School Manager 652

TUTORIAL 10-13: Adding the Payments / All Members function to the Karate School Manager 654

10.7 Introduction to LINQ 661

10.8 Creating Your Own Database 662

TUTORIAL 10-14: Creating the Movie database and the Films table 663

Summary 667 • Key Terms 668 • Review Questions and Exercises 669 • Programming Challenges 671 Chapter 11 Developing Web Applications 677 11.1 Programming for the Web 677

11.2 Creating ASP.NET Applications 681

TUTORIAL 11-1: Creating the Click application 685

11.3 Web Server Controls 690

TUTORIAL 11-2: Student Picnic application 692

11.4 Designing Web Forms 700

TUTORIAL 11-3: Signing up for a Kayak Tour 703

11.5 Applications with Multiple Web Pages 707

TUTORIAL 11-4: Adding a description form to the Kayak Tour application 709

11.6 Using Databases 710

TUTORIAL 11-5: Displaying the Karate Members table in a GridView 713

TUTORIAL 11-6: Updating the Karate Members table 718

Summary 726 • Key Terms 727 • Review Questions and Exercises 728 • Programming Challenges 731 Chapter 12 Classes, Collections, and Inheritance 733 12.1 Classes and Objects 733

12.2 Creating a Class 736

TUTORIAL 12-1: Creating the Student Data application 749

12.3 Collections 753

12.4 Focus on Problem Solving: Creating the Student Collection Application 760

TUTORIAL 12-2: Completing the Student Collection application 760

12.5 The Object Browser 765

TUTORIAL 12-3: Using the Object Browser 765

12.6 Introduction to Inheritance 767

TUTORIAL 12-4: Completing an application that uses inheritance 774

Summary 781 • Key Terms 782 • Review Questions and Exercises 783 • Programming Challenges 790 Appendix A Advanced User Interface Controls and Techniques 795

Appendix B Windows Presentation Foundation (WPF) 809

Appendix C Converting Mathematical Expressions to Programming Statements 821

Appendix D Answers to Checkpoints 823

Appendix E Glossary 841

Index 853

Credits 883

Chapter 1 Forms, Controls, and Properties, p 9

Event-Driven Programming, p 10Tutorial 1-4 Walkthrough, p 21Tutorial 1-5 Walkthrough, p 25Tutorial 1-6 Walkthrough, p 34Solving the Sales Tax Problem, p 41

Chapter 2 Tutorial 2-1 Walkthrough, p 46

Tutorial 2-2 Walkthrough, p 48Tutorial 2-3 Walkthrough, p 50Tutorial 2-5 Walkthrough, p 53Tutorial 2-6 Walkthrough, p 57Responding to Events, p 63Tutorial 2-8 Walkthrough, p 64Tutorial 2-9 Walkthrough, p 68Tutorial 2-10 Walkthrough, p 76Using IntelliSense, p 84

The Name and Address Problem, p 107

Chapter 3 Tutorial 3-2 Walkthrough, p 115

Introduction to Variables, p 124Problem Solving with Variables, p 136Converting TextBox Input, p 149Exception Demonstration, p 161Tutorial 3-10 Walkthrough, p 164

Building a Kayak Rental Application, p 195

The Miles per Gallon Calculator Problem, p 202

Chapter 4 The If ThenStatement, p 211

The If Then ElseStatement, p 217Tutorial 4-2 Walkthrough, p 218

Tutorial 4-3 Walkthrough, p 221Tutorial 4-4 Walkthrough, p 227Validating Input with TryParse, p 254

Improving the Kayak Rental Application, p 272

The Roman Numeral Converter Problem, p 277

Chapter 5 The Do WhileLoop, p 296

Tutorial 5-2 Walkthrough, p 297Tutorial 5-3 Walkthrough, p 301The For NextLoop, p 310

Improving the Kayak Rental Application, p 340

The Sum of Numbers Problems, p 346

Passing Arguments to Procedures, p 363Functions, p 371

Tutorial 6-5 Walkthrough, p 372Tutorial 6-6 Walkthrough, p 380

Improving the Kayak Rental Application, p 393

The Retail Price Calculator Problem, p 396

Chapter 7 Creating and Displaying a Second Form, p 405

Tutorial 7-1 Walkthrough, p 411Creating a Menu, p 435

Adding menus and forms to the Kayak Rental Application, p 456

The Astronomy Helper Problem, p 466

Chapter 8 Accessing Array Elements with a Loop, p 472

Tutorial 8-2 Walkthrough, p 477Tutorial 8-3 Walkthrough, p 480

Using Arrays to Look Up Information in the Kayak Rental Application, p 531

The Lottery Application, p 539

Chapter 9 Writing Data to a File, p 543

Reading Data from a File, p 549Tutorial 9-3 Walkthrough, p 556

Files and Colors in the Kayak Rental Application, p 586

The Random Number File Generator Problem, p 594

Chapter 10 The DataGridView Control, p 602

Data-Bound Controls, p 614Tutorial 10-4 Walkthrough, p 621

Adding a Database to the Kayak Rental Application, p 669

The Karate Members Grid Problem, p 671The Karate Payments by a Single Member Problem, p 674

Chapter 11 Creating a Simple Web Application, p 682

Tutorial 11-2 Walkthrough, p 692Building a Movie Tracking Application, p 728The Stadium Seating Problem, p 731

Chapter 12 Creating a Class, p 737

Collections, p 753Tutorial 12-2 Walkthrough, p 760Kayak Rentals with Classes, p 783The Motor Class Problem, p 791

Preface

Welcome to Starting Out with Visual Basic 2012, Sixth Edition This book is

intended for use in an introductory programming course It is designed for

stu-dents who have no prior programming background, but even experienced stustu-dents will

benefit from its depth of detail and the chapters covering databases, Web applications, and

other advanced topics The book is written in clear, easy-to-understand language and

covers all the necessary topics of an introductory programming course The text is rich in

concise, practical, and real-world example programs, so the student not only learns how to

use the various controls, constructs, and features of Visual Basic, but also learns why and

when to use them

Changes in the Sixth Edition

• The book is completely updated for Visual Basic 2012—This book is designed for

use with Visual Studio 2012 and Visual Studio Express 2012 for Windows Desktop

• Introduction of the StatusStrip Control for Displaying User Messages—The

StatusStrip control is introduced in Chapter 2 as a means for displaying user

mes-sages In many situations, the StatusStrip control is more effective than a message

box because it does not interrupt the user’s workflow

• A New Sequence of VideoNotes has been added throughout the book—Beginning in

Chapter 3, a new sequence of video tutorials that promote an accelerated learning

experience are introduced Each set of tutorials uses topics from the current and

pre-vious chapters to build an application that integrates visual design and interaction

principles Students who wish to accelerate their learning may use these videos to

summarize and apply essential topics in these chapters

• A New Tutorial for Creating a Database—A new tutorial has been added to

Chap-ter 10 showing the student how to create a database within Visual Studio, and add

data to the database

Visual Studio 2012 Express for Windows Desktop

Each new copy of this book comes with Microsoft’s Visual Studio 2012 Express for

Win-dows Desktop—a streamlined product that captures the best elements of Visual Studio in

an ideal format for learning programming The Express edition offers an impressive set of

tools for developing and debugging Visual Basic Windows Forms applications and Web

applications, applications, including those that work with databases and use SQL

A Look at Visual Basic: Past and Present

The first version of Visual Basic was introduced in 1991 Prior to its introduction, writing

a GUI interface for an application was no small task Typically, it required hundreds of

lines of C code for even the simplest Hello World program Additionally, an

understand-ing of graphics, memory, and complex system calls was often necessary Visual Basic was

revolutionary because it significantly simplified this process With Visual Basic, a

programmer could visually design an application’s user interface Visual Basic would then

generate the code necessary to display and operate the interface This allowed the

programmer to spend less time writing GUI code and more time writing code to perform

meaningful tasks

The evolution of Visual Basic from version 1 to version 6 followed a natural progression.Each new release was an improved version of the previous release, providing additionalfeatures and enhancements Visual Basic versions offered backward compatibility, wherecode written in an older version was compatible with a newer version of the Visual Basicdevelopment environment.

In 2002, Microsoft released a new object-oriented software platform known as NET The.NET platform consists of several layers of software that sit above the operating systemand provide a secure, managed environment in which programs can execute In addition

to providing a managed environment for applications to run, NET also provided newtechnologies for creating Internet-based programs and programs that provide servicesover the Web Along with the introduction of the NET platform, Microsoft introduced anew version of Visual Basic known as VB NET 2002, which allowed programmers towrite desktop applications or Web applications for the NET platform

VB NET was not merely a new and improved version of VB 6, however VB NET was atotally new programming environment, and the Visual Basic language was dramaticallyrevised The changes were substantial enough that programs written in earlier versions ofVisual Basic were not compatible with VB NET Microsoft provided a utility that could

be used to convert older Visual Basic applications to the new VB NET syntax, but theresults were not always perfect Although this was frustrating for some Visual Basicdevelopers, Microsoft reasoned the changes were necessary to ensure that Visual Basiccontinued to evolve as a modern, professional programming environment

Microsoft has continued to enhance and improve Visual Basic by regularly releasing newversions The versions, which are named after the year in which they were released, areVisual Basic 2003, Visual Basic 2005, Visual Basic 2008, Visual Basic 2010, and the mostrecent version, Visual Basic 2012

This book is written for Visual Basic 2012 This version of Visual Basic includes severalenhancements that make Visual Basic even more powerful as a professional program-ming system Many of the new features are beyond the scope of this book, and are notcovered The following list summarizes some of the most significant new features of VB2012:

• Introduction of the Async method modifier and the Await statement, for nous programming

asynchro-• Introduction of iterators, to perform custom iterations over collections, lists, andarrays

• A new call hierarchy window in Visual Studio that allows you to display all calls toand from a selected method, property, or constructor

• Caller information attributes that allow you to obtain information about the caller

Organization of the Text

The text teaches Visual Basic step-by-step Each chapter covers a major set of programmingtopics, introduces controls and GUI elements, and builds knowledge as the student pro-gresses through the book Although the chapters can be easily taught in their existingsequence, there is some flexibility The following diagram suggests possible sequences ofinstruction

Chapters 1 through 7 cover the fundamentals of program design, flow control, modular

programming, and the most important Visual Basic controls The instructor may then

continue in any order with Chapters 8, 9, 10, or 12 Part of Chapter 11 relies on database

concepts, so it should be covered after Chapter 10

Brief Overview of Each Chapter

Chapter 1: Introduction to Programming and Visual Basic This chapter

provides an introduction to programming, the programming process, and Visual Basic

GUI programming and the event-driven model are explained The components of

programs, such as keywords, variables, operators, and punctuation are covered, and tools

such as flowcharts and pseudocode are presented The student gets started using the

Visual Basic environment in a hands-on tutorial

Chapter 2: Creating Applications with Visual Basic The student starts by

creat-ing a simple application that displays a graphic image In the tutorials that follow, the

stu-dent adds controls, modifies properties, and enables the application to respond to events

An introduction to the Visual Basic Help system, with a tutorial on debugging, is given.

Chapter 3: Variables and Calculations Variables, constants, and the Visual Basic

data types are introduced The student learns to gather input and create simple arithmetic

statements The intricacies of GUI design are introduced as the student learns about

grouping controls with group boxes, assigning keyboard access keys, and setting the tab

order The student is introduced to exceptions and learns to write simple exception

han-dlers Debugging techniques for locating logic errors are covered

Chapter 4: Making Decisions The student learns about relational operators and how

to control the flow of a program with the If Then, If Then Else, and

If Then ElseIfstatements Logical operators are introduced, and the Select

Casestatement is covered Important applications of these constructs are discussed, such

as testing numeric values, strings, and determining if a value lies within a range, and

vali-dating user input Several string-handling functions and string methods are discussed

Radio buttons and check boxes are also introduced

Chapter 5: Lists and Loops This chapter begins by showing the student how to use

input boxes as a quick and simple way to gather input Next, list boxes and combo boxes

are introduced The chapter covers repetition control structures: the Do While, Do

Until, and For Next loops Counters, accumulators, running totals, and other

loop-related topics are discussed The student also learns how to generate random numbers

Chapter 6: Procedures and Functions The student learns how and why to

modu-larize programs with general-purpose procedures and functions Arguments, parameters,

and return values are discussed Debugging techniques for stepping into and over

proce-dures are introduced

Chapter 7: Multiple Forms, Modules, and Menus This chapter shows how to add

multiple forms to a project and how to create a module to hold procedures and functions

Chapter 11 Chapters 1–7

Chapter 8 Chapter 9 Chapter 10 Chapter 12

that are not associated with a specific form It covers creating a menu system, with mands and submenus that the user may select from.

com-Chapter 8: Arrays and More This chapter discusses both single dimension and

multi-dimensional variable arrays Many array programming techniques are presented, such assumming all the elements in an array, summing all the rows or columns in a two-dimensionalarray, searching an array for a specific value, sorting arrays, and using parallel arrays TheEnabled property, timer controls, and control anchoring and docking are also covered

Chapter 9: Files, Printing, and Structures This chapter begins by discussing how

to save data to sequential text files and then read the data back into an application TheOpenFileDialog, SaveFileDialog, FontDialog, and ColorDialog controls are introduced.The PrintDocument control is discussed, with a special focus on printing reports Thechapter shows the student how to create user-defined data types with structures

Chapter 10: Working with Databases This chapter introduces basic database

con-cepts The student learns how to display a database table in a DataGridView control andwrite applications that display, sort, and update database data The Structured QueryLanguage (SQL) is introduced An application that shows how to display database data inlist boxes, text boxes, labels, and combo box is presented The chapter concludes with anoverview of Language Integrated Query (LINQ)

Chapter 11: Developing Web Applications This chapter shows the student how to

create ASP.NET applications that run on Web Browsers such as Internet Explorer,Chrome, Firefox, and Safari Using Microsoft Visual Studio, or Microsoft Visual WebDeveloper, the student learns how to use Web server controls and Web forms to buildinteractive, database-driven Web applications

Chapter 12: Classes, Collections, and Inheritance This chapter introduces classes

as a tool for creating abstract data types The process of analyzing a problem and mining its classes is discussed, and techniques for creating objects, properties, and methodsare introduced Collections are presented as structures for holding groups of objects The

deter-Object Browser, which allows the student to see information about the classes, properties,

methods, and events available to a project, is also covered The chapter concludes by ducing inheritance, and shows how to create a class that is based on an existing class

intro-Appendix A: Advanced User Interface Controls and Techniques Discusses

many of the more advanced controls available in Visual Basic, as well as several helpfulprogramming techniques This appendix also provides a summary of common user inter-face design guidelines

Appendix B: Windows Presentation Foundation (WPF) Introduces the student

to the Windows Presentation Framework (WPF), and includes a tutorial in which the studentcreates a simple WPF application

Appendix C: Converting Mathematical Expressions to Programming Statements Shows the student how to convert a mathematical expression into a Visual

Basic programming statement

Appendix D: Answers to Checkpoints Students may test their progress by

com-paring their answers to Checkpoints with the answers provided The answers to allCheckpoints are included

Appendix E: Glossary Provides a glossary of the key terms presented in the text.

The following appendixes are located on the Student CD-ROM:

Appendix F: Visual Basic 2012 Function and Method Reference Provides a

reference for the functions and methods that are covered in the text The exceptions thatmay be caused by these functions and methods are also listed

Appendix G: Binary and Random-Access Files Describes programming techniques

for creating and working with binary and random-access data files

The following appendix is available on the Companion Website for this book at http://www.pearsonhighered.com/gaddisvb/

Features of the Text

Concept Statements Each major section of the text starts with a concept statement.

This statement concisely summarizes the meaning of the section

Tutorials Each chapter has several hands-on tutorials that reinforce the chapter’s topics.

Many of these tutorials involve the student in writing applications that can be applied to

real-world problems

VideoNotes A series of online videos, developed specifically for this book, are available

for viewing at http://www.pearsonhighered.com/gaddisvb/ Icons appear

throughout the text alerting the student to videos about specific topics

Checkpoints Checkpoints are questions placed at intervals throughout each chapter.

They are designed to query the student’s knowledge immediately after learning a new

topic Answers to all the Checkpoints are provided in Appendix D

Notes Notes are short explanations of interesting or often misunderstood points

relevant to the topic being discussed

Tips Tips advise the student on the best techniques for approaching different

program-ming problems and appear regularly throughout the text

Warnings Warnings caution the student about certain Visual Basic features, programming

techniques, or practices that can lead to malfunctioning programs or lost data

Review Questions and Exercises In the tradition of all Gaddis texts, each chapter

presents a thorough and diverse set of review questions and exercises These include

tra-ditional fill-in-the-blank, true or false, multiple choice, and short answer questions There

are also unique tools for assessing a student’s knowledge For example, Find the Error

questions ask the student to identify syntax or logic errors in brief code segments

Algorithm Workbench questions ask the student to design code segments to satisfy a given

problem There are also What Do You Think? questions that require the student to think

critically and contemplate the topics presented in the chapter

Programming Challenges Each chapter offers a pool of programming exercises

designed to solidify the student’s knowledge of the topics at hand In most cases, the

assignments present real-world problems to be solved When applicable, these exercises

also include input validation rules

Supplements

Student

The following supplementary material is bundled with the book:

• Source code and files required for the chapter tutorials are available at the book’s

companion website: www.pearsonhighered.com/gaddisvb The website also

con-tains Appendix F, Visual Basic 2012 Function and Method Reference, and Appendix G, Binary and Random-Access Files.

• Microsoft Visual Studio 2012 Express for Windows Desktop

VideoNote

The following supplements are available to qualified instructors:

• Answers to all Review Questions in the text

• Solutions for all Programming Challenges in the text

• PowerPoint presentation slides for every chapter

• Test bank

• Test generation software that allows instructors to create customized testsFor information on how to access these supplements, visit the Pearson EducationInstructor Resource Center at http://www.pearsonhighered.com/irc/ or send e-mail to computing@aw.com

Online Practice and Assessment with MyProgrammingLab

MyProgrammingLab is a web-based service that helps students fully grasp the logic, tics, and syntax of programming Through practice exercises and immediate, personalizedfeedback, MyProgrammingLab improves the programming competence of beginning stu-dents who often struggle with the basic concepts and paradigms of popular high-level pro-gramming languages A self-study and homework tool, a MyProgrammingLab courseconsists of hundreds of small practice exercises organized around the structure of this text-book For students, the system automatically detects errors in the logic and syntax of theircode submissions and offers targeted hints that enable students to figure out what wentwrong For instructors, a comprehensive gradebook tracks correct and incorrect answers andstores the code inputted by students for review

seman-For a full demonstration, to see feedback from instructors and students, or to get startedusing MyProgrammingLab in your course, visit MyProgrammingLab.com

Web Resources

Self-assessment quizzes, PowerPoint slides, source code files, and glossary flashcards are

avail-able on the Companion Website for Starting Out with Visual Basic 2012 at http://www.

pearsonhighered.com/gaddisvb/

Acknowledgments

There were many helping hands in the development and publication of this text Theauthors would like to thank the following faculty reviewers for their helpful suggestionsand expertise during the production of this edition:

Paul Bladek, Edmonds Community College

Arthur E Carter, Radford University

Jesse Cecil, College of the Siskiyous

Sallie Dodson, Radford University

Jackie Horton, University of Vermont

Darrel Karbginsky, Chemeketa Community

College

Frank J Kreimendahl, University of New

Hampshire

Jing Liu, Southeastern Louisiana University

Solomon Negash, Kennesaw State University

Robert Nields, Cincinnati State Technical and

Community College

Alison Pechenick, University of Vermont Richard Pelletier, San Diego City College Pete Sanderson, Otterbein University Gurmukh Singh, SUNY Fredonia Judith A Stafford, Tufts University Doug Waterman, Fox Valley Technical College Erik Wynters, Bloomsburg University of

Pennsylvania

Achla Agarwal, Bossier Parrish Community

College

Ronald Bass, Austin Community College

Ronald Beauchemin, Springfield Technical

Community College

Zachory T Beers, Microsoft Corporation

Robert M Benavides, Collin County Community

Harold Broberg, Indiana Purdue University

Nancy Burns, Professor of Computer Science,

Chipola College

Mara Casado, State College of Florida,

Manatee-Sarasota

Joni Catanzaro, Louisiana State University

Dr Robert Coil, Cincinnati State Community and

Technical College

Carol A DesJardins, St Clair County Community

College

William J Dorin, Indiana University

Robert Ekblaw, SUNY Albany

Rose M Endres, City College of San Francisco

Jean Evans, Brevard Community College

Mark Fienup, University of Northern Iowa

Pierre M Fiorini, PhD, University of Southern

Maine

Arlene Flerchinger, Chattanooga State Technical

Community College

Lawrence Fudella, Erie Community College

Gail M Gehrig, Florida Community College at

Jacksonville

Jayanta Ghosh, Florida Community College

Iskandar Hack, Indiana University—Purdue

University at Fort Wayne

Tom Higginbotham, Southeastern Louisiana

University

Dennis Higgins, SUNY Oneonta

David M Himes, Oklahoma State University,

Okmulgee

Greg Hodge, Northwestern Michigan College

Corinne Hoisington, Central Virginia Community

University

Juan Marquez, Mesa Community College Gary Marrer, Glendale Community College Norman McNeal, Dakota County Technical

Robert Nields, Cincinnati State Community and

College

Margaret Warrick, Allan Hancock College Elaine Yale Weltz, Seattle Pacific University Floyd Jay Winters, Program Director,

Computer Science, College of Florida, Manatee-Sarasota

Catherine Wyman, DeVry Institute,

Phoenix

Sheri L York, Ball State University

The authors would like to thank their families for their tremendous support throughout this

project We would also like to thank everyone at Pearson Addison-Wesley who was part of

our editorial, production, and marketing team We are fortunate to have Matt Goldstein as

our editor for this book He and Jenah Blitz-Stoehr, editorial assistant, guided us through the

delicate process of revising the book The production team, led by Marilyn Lloyd, did a

tremendous job to make this book a reality We are also fortunate to work with Yez Alayan,

Marketing Manager, and Kathryn Ferranti, Marketing Coordinator They do a great job

getting this book out to the academic community You are all great people to work with!

Reviewers of the Previous Editions

About the Authors

Tony Gaddis is the principal author of the Starting Out with series of textbooks Tony

has nearly two decades of experience teaching computer science courses, primarily atHaywood Community College in North Carolina He is a highly acclaimed instructor

who was previously selected as North Carolina’s Community College Teacher of the

Year, and has received the Teaching Excellence award from the National Institute for

Staff and Organizational Development Besides Visual Basic books, the Starting Out

with series includes introductory books on programming logic and design, Alice, the

C++ programming language, Java™, Python, and Microsoft® C#®, all published byPearson Addison-Wesley

Kip Irvine holds M.S (computer science) and D.M.A (music composition) degrees from

the University of Miami He was formerly on the faculty at Miami-Dade CommunityCollege, and is presently a member of the School of Computing and Information Sciences

at Florida International University His published textbooks include COBOL for the

IBM Personal Computer, Assembly Language for Intel-Based Computers, C++ and Object-Oriented Programming, and Advanced Visual Basic NET.

Attention Students

Installing Visual Basic

To complete the tutorials and programming problems in this book, you need to install

Visual Basic 2012 on your computer When purchased new, this textbook is packaged

with a Microsoft DVD that contains Visual Studio 2012 Express for Windows Desktop.

Install this on your computer before starting any of the book’s tutorials

If you plan to work through Chapter 11, you will also need to install Visual Web

Devel-oper 2012 Express, which is available on the accompanying Microsoft DVD.

If your book does not have the accompanying Microsoft DVD, you can download both

Visual Studio 2012 Express for Windows Destktop and Visual Web Developer 2012

Express from the following Web site:

http://www.microsoft.com/express/Downloads/

N O T E : If you are working in your school’s computer lab, there is a good chance that

Microsoft Visual Studio has been installed, rather than Visual Studio Express If this is

the case, your instructor will show you how to start Visual Studio The tutorials in this

book can be completed with either Visual Studio 2012 or Visual Studio 2012 Express

for Windows Desktop

Installing the Student Sample Program Files

The Student Sample Program files that accompany this book are available for download

from the book's companion Web site at:

http://www.pearsonhighered.com/gaddisvb

These files are required for many of the book’s tutorials Simply download the Student

Sample Program files to a location on your hard drive where you can easily access them

Through the power of practice and immediate personalized feedback, MyProgrammingLab improves your performance.

get with the programming

T O P I C S

Introduction to Programming and Visual Basic

Microsoft Visual Basic is a powerful software development system for creating

applica-tions that run on the Windows operating system With Visual Basic, you can do the

following:

• Create applications with graphical windows, dialog boxes, and menus

• Create applications that work with databases

• Create Web applications and applications that use Internet technologies

• Create applications that display graphics

Visual Basic, which is commonly referred to as VB, is a favorite tool among professional

programmers It provides tools to visually design an application’s appearance, a modern

programming language, and access to the latest Microsoft technologies Powerful

appli-cations can be created with Visual Basic in a relatively short period of time

Before plunging into learning Visual Basic, we will review the fundamentals of computer

hardware and software, and then become familiar with the Visual Studio programming

Computer Systems: Hardware and Software

C O N C E P T: Computer systems consist of similar hardware devices and

hard-ware components This section provides an overview of computer hardware and software organization.

HardwareThe term hardware refers to a computer’s physical components A computer, as we gener-

ally think of it, is not an individual device, but rather a system of devices Like theinstruments in a symphony orchestra, each device plays its own part A typical computersystem consists of the following major components:

1 The central processing unit (CPU)

2 Main memory

3 Secondary storage devices

4 Input devices

5 Output devicesThe organization of a computer system is shown in Figure 1-1

1.1

Input Devices

Output Devices

Secondary Storage Devices

Central Processing Unit

Main Memory (RAM)

Figure 1-1 The organization of a computer system

1 The CPU

When a computer is performing the tasks that a program tells it to do, we say that the

computer is running or executing the program The central processing unit, or CPU, is the

part of a computer that actually runs programs The CPU is the most important component

in a computer because without it, the computer could not run software

A program is a set of instructions that a computer’s CPU follows to perform a task The

program’s instructions are stored in the computer’s memory, and the CPU’s job is to fetch

those instructions, one by one, and carry out the operations that they command In

mem-ory, the instructions are stored as a series of binary numbers A binary number is a

se-quence of 1s and 0s, such as

11011011

This number has no apparent meaning to people, but to the computer it might be an instruction to multiply two numbers or read another value from memory

2 Main Memory

You can think of main memory as the computer’s work area This is where the computer

stores a program while the program is running, as well as the data that the program is

working with For example, suppose you are using a word processing program to write an

essay for one of your classes While you do this, both the word processing program and the

essay are stored in main memory

Main memory is commonly known as random-access memory, or RAM It is called this

because the CPU is able to quickly access data stored at any random location in RAM

RAM is usually a volatile type of memory that is used only for temporary storage while a

program is running When the computer is turned off, the contents of RAM are erased

Inside your computer, RAM is stored in microchips

3 Secondary Storage

The most common type of secondary storage device is the disk drive A disk drive stores

data by magnetically encoding it onto a circular disk Most computers have a disk drive

mounted inside their case External disk drives, which connect to one of the computer’s

communication ports, are also available External disk drives can be used to create backup

copies of important data or to move data to another computer

In addition to external disk drives, many types of devices have been created for copying

data, and for moving it to other computers For many years floppy disk drives were

pop-ular A floppy disk drive records data onto a small floppy disk, which can be removed

from the drive The use of floppy disk drives has declined dramatically in recent years, in

favor of superior devices such as USB drives USB drives are small devices that plug into

the computer’s USB (universal serial bus) port, and appear to the system as a disk drive

USB drives, which use flash memory to store data, are inexpensive, reliable, and small

enough to be carried in your pocket

Optical devices such as the CD (compact disc) and the DVD (digital versatile disc) are also

popular for data storage Data is not recorded magnetically on an optical disc, but is

en-coded as a series of pits on the disc surface CD and DVD drives use a laser to detect the

pits and thus read the encoded data Optical discs hold large amounts of data, and

be-cause recordable CD and DVD drives are now commonplace, they are good mediums for

creating backup copies of data

4 Input Devices

Input is any data the computer collects from the outside world The device that collects the

data and sends it to the computer is called an input device Common input devices are the

keyboard, mouse, scanner, and digital camera Disk drives and CD drives can also be

con-sidered input devices because programs and data are retrieved from them and loaded into

the computer’s memory

5 Output Devices Output is any data the computer sends to the outside world It might be a sales report, a list

of names, a graphic image, or a sound The data is sent to an output device, which formats

and presents it Common output devices are monitors and printers Disk drives and CDrecorders can also be considered output devices because the CPU sends data to them inorder to be saved

Software

Software refers to the programs that run on a computer There are two general categories of

software: operating systems and application software An operating system or OS is a set

of programs that manages the computer’s hardware devices and controls their processes.Windows, Mac OS, and Linux are all operating systems

Application software refers to programs that make the computer useful to the user These

programs, which are generally called applications, solve specific problems or performgeneral operations that satisfy the needs of the user Word processing, spreadsheet, anddatabase packages are all examples of application software As you work through thisbook, you will develop application software using Visual Basic

Checkpoint

1.1 List the five major hardware components of a computer system

1.2 What is main memory? What is its purpose?

1.3 Explain why computers have both main memory and secondary storage

1.4 What are the two general categories of software?

Programs and Programming Languages

C O N C E P T: A program is a set of instructions a computer follows in order to

perform a task A programming language is a special language used

to write computer programs.

What Is a Program?

Computers are designed to follow instructions A computer program is a set of instructionsthat enables the computer to solve a problem or perform a task For example, suppose we

want the computer to calculate someone’s gross pay—a Wage Calculator application.

Figure 1-2 shows a list of things the computer should do

Collectively, the instructions in Figure 1-2 are called an algorithm An algorithm is a set of

well-defined steps for performing a task or solving a problem Notice these steps aresequentially ordered Step 1 should be performed before Step 2, and so on It is importantthat these instructions are performed in their proper sequence

1.2

States and Transitions

It is helpful to think of a running computer program as a combination of states and

transi-tions Each state is represented by a snapshot (like a picture) of the computer’s memory

Using the Wage Calculator application example from Figure 1-2, the following is a memory

snapshot taken when the program starts:

In Step 3, the number of hours worked by the user is stored in memory Suppose the user

enters the value 20 A new program state is created:

In Step 6, the hourly pay rate entered by the user is stored in memory Suppose the user

enters the value 25 The following memory snapshot shows the new program state:

Figure 1-2 Program steps—Wage Calculator application

1 Display a message on the screen: How many hours did you work?

2 Allow the user to enter the number of hours worked

3 Once the user enters a number, store it in memory

4 Display a message on the screen: How much do you get paid per hour?

5 Allow the user to enter an hourly pay rate

6 Once the user enters a number, store it in memory

7 Once both the number of hours worked and the hourly pay rate are entered, multiply

the two numbers and store the result in memory as the gross pay

8 Display a message on the screen that shows the gross pay The message must include

the result of the calculation performed in Step 7

In Step 7, the application calculates the amount of money earned, saving it in memory.The following memory snapshot shows the new program state:

The memory snapshot produced by Step 7 represents the final program state

Programming Languages

In order for a computer to perform instructions such as the wage calculator algorithm, thesteps must be converted to a format the computer can process As mentioned earlier, a pro-gram is stored in memory as a series of binary numbers These numbers are known as

machine language instructions The CPU processes only instructions written in machine

language Our Wage Calculator application might look like the following at the moment

when it is executed by the computer:

10101101110101000111100001101110100011110001110011010101110 etc.

The CPU interprets these binary or machine language numbers as commands As youmight imagine, the process of encoding an algorithm in machine language is tedious and

difficult Programming languages, which use words instead of numbers, were invented to

ease this task Programmers can write their applications in programming language

state-ments, and then use special software called a compiler to convert the program into

machine language Names of some popular recent programming languages are shown inTable 1-1 This list is only a small sample—there are thousands of programming languages

Table 1-1 Popular programming languages

Language Description

Visual Basic, C# Popular programming languages for building Windows and Web applications

C, C++ Powerful advanced programming languages that emphasize flexibility and fast

running times C++ is also object-oriented

Java Flexible and powerful programming language that runs on many different

computer systems Often used to teach object-oriented programming

Python Simple, yet powerful programming language used for graphics and small

applications

PHP Programming language used for creating interactive Web sites

JavaScript Scripting language used in Web applications that provides rich user interfaces

for Web browsers

What Is a Program Made Of?

All programming languages, including Visual Basic, have certain elements in common Let’slook at the major programming language elements that you will work with when writing aprogram

Keywords (Reserved Words)

Each high-level language has its own set of words that the programmer must learn in order

to use the language The words that make up a high-level programming language are

known as keywords or reserved words Each keyword has a specific meaning and cannot

be used for any other purpose As you work through this book you will learn many of the

Visual Basic keywords and how to use them in a program

Operators

In addition to keywords, programming languages have operators that perform various

op-erations on data For example, all programming languages have math operators that

per-form arithmetic In Visual Basic, as well as most other languages, the  sign is an operator

that adds two numbers The following would add 12 and 75:

12 + 75

Variables

Programs use variables to store data in memory A variable is a storage location in memory

that is represented by a name When a value is stored in a variable, it is stored in the

com-puter’s memory

Programmers make up the names for all the variables that they use in a program You will

learn specific rules and guidelines for naming variables in Chapter 3, but for now just

re-member that a variable’s name is a single word that indicates what the variable is used for

For example, a program that calculates the sales tax on a purchase might use a variable

named taxto hold that value in memory And a program that calculates the distance from

Earth to a star might use a variable named distanceto hold that value in memory When

a program stores a value in a variable, the value is actually stored in memory at the

loca-tion represented by the variable

Syntax

In addition to keywords and operators, each language also has its own syntax, which is a

set of rules that must be strictly followed when writing a program The syntax rules dictate

how keywords, operators, and various punctuation characters must be used in a program

When you are learning a programming language, you must learn the syntax rules for that

particular language

N O T E : Human languages also have syntax rules Do you remember when you took

your first English class, and you learned all those rules about infinitives, indirect objects,

clauses, and so forth? You were learning the syntax of the English language

Although people commonly violate the syntax rules of their native language when

speaking and writing, other people usually understand what they mean Unfortunately,

program compilers do not have this ability If even a single syntax error appears in a

program, the program cannot be compiled or executed

Statements

The individual instructions that you write in a program are called statements A

program-ming statement can consist of keywords, operators, punctuation, and other allowable

pro-gramming elements, arranged in the proper sequence to perform an operation The

statements that are written in a program are commonly called source code, or simply code.

A procedure is a set of programming statements that exist within a program for the purpose

of performing a specific task The program executes the procedure when the task needs to

be performed

Comments (Remarks)

Not everything that the programmer writes in a program is meant to be executed by the

computer Some parts of a program are comments, or remarks, that help the human reader

of a program understand the purposes of the program statements In Visual Basic, anystatement that begins with an apostrophe (’) is considered a comment When the VisualBasic compiler sees a statement that begins with an apostrophe, it recognizes it as a com-ment and it skips over it

You should always add descriptive comments to your code The extra time it takes is wellspent Sometimes you (the programmer) will have to reread and understand your owncode Comments are a great way to remind you of what you were thinking when you cre-ated the program In addition, you may have to modify or maintain code written byanother programmer and you will appreciate the time spent to write comments!

Graphical User Interfaces

When a computer program is needed to perform a task, the programmer is the person whodevelops the algorithm, and writes the programming statements that perform the algo-rithm’s steps Once the program is complete, it is made available to those who need to use

it The people who use the program are known as users.

Although the programmer works directly with a program’s statements, users are typicallynot concerned with the program’s inner workings Users want to make sure that theyknow how to operate the program when it is running, and that the program works as it

should The part of a program that users interact with is known as the user interface On

modern operating systems such as Windows, most of the programs that people use have a

graphical user interface, or GUI (pronounced gooey) A graphical user interface typically

consists of one or more windows that appear on the computer screen A window is a

rec-tangular area that contains other visual elements such as text, buttons that can be clickedwith the mouse, boxes that accept keyboard input, and so forth Let’s look at an example.Follow the steps in Tutorial 1-1 to run a program that you can download from the book’scompanion Website, at www.pearsonhighered.com/gaddisvb

Tutorial 1-1:

Running the Wage Calculator application

text-book’s companion Website, at www.pearsonhighered.com/gaddisvb If you areworking in your school’s computer lab, your instructor will tell you where thefiles are located

Double-click the file Wage Calculator.exe (the exe filename extension may not be

visi-ble) The program’s window should display as shown in Figure 1-3 Leave theprogram running as you continue to read We will perform operations with theprogram in Tutorial 1-2

The program that you executed in Tutorial 1-1 calculates an employee’s gross pay Notice

that inside the program’s window (shown in Figure 1-3) there are boxes for entering the

number of hours worked and the hourly pay rate There is also a button that calculates

the gross pay when it is clicked with the mouse, and a button that closes the program

(stops its execution) All of these elements are part of the program’s GUI, and anyone

operating the program will interact with these elements

In addition to being a programming language, Visual Basic is also a programming

envi-ronment that provides tools for creating an application’s graphical user interface With

Visual Basic you can design the appearance of an application’s GUI and write the code

that makes the application work

Objects and Controls

As a student studying Visual Basic, you will frequently encounter two terms: object and

control An object is an item in a program that contains data and has the ability to perform

operations The data that an object contains is referred to as properties, or attributes The

operations that an object can perform are called methods (Recall that earlier we

men-tioned that a procedure is a set of programming statements that exist within a program

for the purpose of performing a specific task A method is a special type of procedure that

belongs to an object.)

In the beginning of your studies you will learn how to use many different objects that are

provided by Visual Basic to perform various operations in your programs In Chapter 12,

you will learn to define your own objects

A control is a specific type of object that usually appears in a program’s graphical user

in-terface For example, each of the elements that appear in the user interface in Figure 1-3 is

a control The window that contains the other elements is known as a Form control The

small boxes that accept keyboard input are known as TextBox controls The areas that

simply display text are known as Label controls The buttons that perform operations

when clicked with the mouse are known as Button controls Figure 1-4 points out each of

these controls in the user interface

Figure 1-3 A graphical user interface

N O T E : Visual Basic is an object-oriented programming (OOP) language A typical VB

application uses numerous objects (such as GUI controls) that work together

Forms,

Controls, and

Properties

VideoNote

A GUI control’s visual appearance is determined by the control’s properties A property is

simply a piece of data that determines some characteristic of the control For example,

many controls have a Text property that determines the text that is displayed by the

con-trol If you look at Figure 1-4, near the top of the form you see a Label control that displays

the text Number of Hours Worked That Label control’s Text property is set to the value

Number of Hours Worked Just below that Label is another Label control, and its Text

property is set to the value Hourly Pay Rate.

Button controls also have a Text property In Figure 1-4, the leftmost button’s Text

prop-erty is set to the value Calculate Gross Pay, and the rightmost button’s Text propprop-erty is set

to the value Close Forms have a Text property too, which determines the text that is

dis-played in the title bar at the top of the form In Figure 1-4, the form’s Text property is set

to Wage Calculator Part of the process of creating a Visual Basic application is deciding

what values to store in each object’s properties

Event-Driven ProgrammingPrograms that operate in a GUI environment must be event-driven An event is an action

that takes place within a program, such as the clicking of a control All Visual Basic trols are capable of detecting various events For example, a Button control can detect when

con-it has been clicked and a TextBox control can detect when con-its contents have changed Names are assigned to all of the events that can be detected For instance, when the userclicks a Button control, a Click event occurs When the contents of a TextBox controlchanges, a TextChanged event occurs If you wish for a control to respond to a specific

event, you must write a set of programming statements known as an event handler An

event handler is a special type of procedure that executes when a specific event occurs

(Event handlers are also known as event procedures.) If an event occurs, and there is no

event handler to respond to that event, the event is ignored

Part of the Visual Basic programming process is designing and writing event handlers

Tutorial 1-2 demonstrates an event handler using the Wage Calculator application you

Event-Driven

Programming

VideoNote