Sams Teach Yourself Visual Basic 6 in 24 Hours

By Greg Perry

• Table of Contents
  • Copyright
  • About the Author
  • Acknowledgments
  • Introduction
  • Who Should Read This Book
  • What This Book Will Do for You
  • Can This Book Really Teach Visual Basic in 24 Hours?
  • What You Need
  • Files on the Visual Basic Distribution CD-ROM
  • Conventions Used in This Book
  • Enough! Time Is Ticking!
  • Part I: Introducing Visual Basic
  • Hour 1. Visual Basic at Work
  • Hour 2.Analyzing Visual Basic Programs
  • Hour 3.Controls and Properties
  • Hour 4.Examining Labels, Buttons, and Text Boxes
  • Part II: Coding the Details
  • Hour 5.Putting Code into Visual Basic
  • Hour 6.Message and Input Boxes
    • A Function Preview
    • A MsgBox() and InputBox() Overview
    • Visual Basic's Code Window Help
    • A Short Detour: Remarks
    • Examining InputBox()
    • Summary
    • Q&A
    • Workshop
  • Hour 7.Making Decisions
  • Hour 8.Visual Basic Looping
  • Part III:Putting Code to Work
  • Hour 9.Combining Code and Controls
  • Hour 10.List Boxes and Data Lists
  • Hour 11.Additional Controls
  • Hour 12.Dialog Box Basics
  • Part IV:Programming with Data
  • Hour 13.Modular Programming
  • Hour 14.Built-In Functions Save Time
  • Hour 15.Visual Basic Database Basics
  • Hour 16.Printing with Visual Basic
  • Part V:Sprucing Up Programs
  • Hour 17.Menus and Visual Basic
  • Hour 18.The Graphic Image Controls
  • Hour 19.Toolbars and More Graphics
  • Hour 20.Writing Correct Applications
  • Part VI:Advancing Visual Basic Applications
  • Hour 21.Visual Basic and ActiveX
  • Hour 22.Object Basics
  • Hour 23.Distributing Your Applications
  • Hour 24.Online Visual Basic
  • Part VII:Appendixes
  • Appendix A.Operator Precedence
  • Appendix B.Answers
  • Appendix C.Using the CD-ROM

A Function Preview

Visual Basic includes several built-in functions (often called intrinsic functions) that do work for you. Many functions perform common mathematical tasks such as computing a square root. Other functions manipulate string data such as converting text inside a string to uppercase or lowercase letters. Other functions, such as the functions taught in this lesson, perform input and output.

A function is a routine that accepts zero, one, or more arguments and returns a single result. An intrinsic function is a function supplied with Visual Basic.

A function takes zero, one, or more arguments and converts those arguments to a single return value. Figure 6.1 shows an overview of a function's job. The most important thing to remember is that a function always returns a single value.

Figure 6.1 A function accepts arguments and returns a single value.

An argument is a value you pass to a function so the function has data to work with.

A function's job is to save you time. For example, if you need to compute the square root of a user-entered value, you could write the assignments and expressions to compute the square root. The square root, however, is such a common routine that Microsoft wrote the code once and stored the square root routine in an intrinsic function. Now, if you want the square root of a value, you'll pass the value as a single argument to the square root function, and after performing the necessary math, the square root function will return the root.

This lesson focuses on two intrinsic functions that don't do math. Instead, they display messages or receive user input. Don't worry too much about what a function is as long as you have the general idea. You'll become much more familiar with them before you're through with this tutorial.

This lesson spends the rest of the hour teaching you these functions:

• MsgBox()
• InputBox()

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