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you would create your own template and add it to Visual Basic Express？
3。 In the Solution Explorer； each item in the tree control represents a single item （such as
a file； user interface control； and so on）。 If you were to double…click a 。vb file； you would
be manipulating a Visual Basic file that would contain Visual Basic code。 Should a single
Visual Basic file reference a single Visual Basic class or namespace？ And if not； how
would you organize your Visual Basic code with respect to Visual Basic files？
4。 You have learned about how a application can generate an executable file。 Let’s
say that you take the generated application and execute it on another Windows
puter。 Will the generated application run？ Let’s say that you take the executable file to a
Macintosh OS X or Linux puter； will the application run？ Why will it run or not run？
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C H AP TE R 1 ■ R E AD Y ； ST E AD Y ； G O！ 23
5。 You are not happy with the naming of the element TextBox1； and want to rename it to
TxtOutput。 How do you go about renaming TextBox1？
6。 ClassLibrary has embedded logic that assumes the caller of the method is a console
application。 Is it good to assume a specific application type or logic of the caller in a
library？ If yes； why？ If no； why not？
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C H A P T E R 2
■ ■ ■
Learning About Number
and Value Types
In the previous chapter； you learned how to use Visual Basic Express； and what is in terms of
the CIL and CLR。 In this chapter； we are going to roll up our sleeves and begin writing real
Visual Basic code—specifically； a calculator。
A calculator is an ideal example to start with； because it allows you to focus on the applica
tion without having to deal with all the nasty details that are normally associated with programs。
In a programming language like Visual Basic； adding two numbers is trivial。 What is not trivial
is how to put the operation of adding two numbers into a program。
This chapter focuses on the mechanics of writing a program in Visual Basic—taking an
idea and converting it into a Visual Basic program that can execute your intentions。 You’ll learn
how to organize your development and implement a Visual Basic class library； as well as how
the CLR manages number types。
Focusing and Organizing Your Development
When you develop software； you will split your work into two main tasks： organizing and imple
menting。 Organizing your development involves figuring out what features and libraries you
are going to define； how many people are going to be developing the features； and so on。
Organizing your development is one of the most important tasks when writing code； and
it is also typically the most confusing for new developers。 Professional developers seem to
organize their work instinctively； but it only appears that way because they have done it so
many times that the process has bee automatic。
When developers are tasked with creating a program； they are asked to write software that
implements a set of features。 Features could include calculating daily interest payments； auto
matically generating letters indicating the acceptance or rejection of a loan； and so on。 A feature
always relates to performing some task that is determined by some process。 You could say that
feature implementation is the direct implementation of a task。
25
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26 CH AP T E R 2 ■ L E A R N IN G AB OU T 。 N E T N U M B E R A N D V A L U E T Y P E S
When defining the features； two major steps are involved：
o Gain an understanding of the features。 You can’t implement something that you don’t
understand。 To be able to write the source code for a feature； you need to know the whys
and whats of a feature。
o Describe the features using structured design methods。 Simply organizing your thoughts
may be enough if you are the only person working on a program； however； more often than
not； you will be part of a team。 You need to use a structured design method so that you and
your team members can municate the thoughts related to program development。
One mon structured design method is the Unified Modeling Language （UML）。 UML is
used to organize the features into units that correspond to programming language constructs；
such as classes。 Think of UML as software developer…specific lingo used to describe the various
aspects of a programming environment at a higher level of abstraction。 UML allows you to get
an overall understanding of the architecture without having to read the source code。 Think of
UML as the structured doodle on the napkin of software programming。
Along with UML； there are other ways of structuring your development process。 For example；
another technique is called agile software development。 The idea with agile software develop
ment is to use a whiteboard and develop your own structured munication mechanism。
The choice of UML； agile software development； or another structured design method is
up to you and your team members。 But you will need to organize your thoughts and have a
structured munication technique。 If you don’t； your software will be late； buggy； too
expensive； or inplete。 It is not an understatement to say that organization is half the battle。
In this chapter； I am going to give you a taste of a simplified structured development tech
nique； so that you at least have an idea of how structured development works。
Organizing the Calculator
To begin this chapter’s example； get a piece of paper and a pen or pencil； or you can use a tablet
PC for writing； if you have one。 Next； in the center of the paper （or virtual paper）； draw a circle
and in it write the word Calculator。 Now stop and think about what a calculator means with
respect to the software that you will be writing。 Write those ideas on the paper surrounding the
circle。 My thoughts are shown in Figure 2…1。
Your thoughts and my thoughts may or may not be the same； but what our results will have
in mon is a hodgepodge of ideas everywhere。 Figure 2…1 illustrates that one of the biggest
problems software developers face is lack of focus and organization。 It is not that developers
can’t focus or organize； but that developers are bombarded by information； and it is a Herculean
task to keep track of； let alone organize； all of that information。 But software projects that are
successful must remain focused and organized。 Therefore； the next step is to focus and organize
your thoughts； which results in something like Figure 2…2。
In Figure 2…2； the ideas are organized by classification。 As this is book is about a program
ming language； the only relevant ideas are those related to source code functionality。 Roughly
speaking； in the source code category； each thought corresponds to a fea