Visual Basic.NET 2008 > Using Variables and Data Types

Types of Variables in Visual Basic 2008

Visual Basic recognizes the following five categories of variables:

• Numeric

• String

• Boolean

• Date

• Object

The two major variable categories are numeric and string. Numeric variables store numbers, and string variables store text. Object variables can store any type of data. Why bother to specify the type if one type suits all? On the surface, using object variables might seem like a good idea, but they have their disadvantages. Integer variables are optimized for storing integers, and date variables are optimized for storing dates. Before VB can use an object variable, it must determine its type and perform the necessary conversions. If the variable is declared with a specific type, these conversions are not necessary.

We begin our discussion of variable types with numeric variables. Text is stored in string variables, but numbers can be stored in many formats, depending on the size of the number and its precision. That's why there are many types of numeric variables. The String and Date data types are much richer in terms of the functionality they expose, and are discussed in more detail in Chapter, ‘‘Handling Strings, Characters, and Dates.''

More on Types of Variable:

• Numeric Variables
• Integer Variables
  • Single- and Double-Precision Numbers
  • The Decimal Data Type
• Infinity and Other Oddities
• Testing for Infinity and NaN
• Byte Variables
• Boolean Variables
• String Variables
• Character Variables
• Date Variables
• Data Type Identifiers

Table of Contents

• VB.NET Variables
• Declaring Variables in VB 2008
• Types of Variables in VB.NET 2008
• The Strict, Explicit, and Infer Options
• Object Variables
• Variables as Objects
• Converting Variable Types
• Formatting Numbers
• User-Defined Data Types
• Examining Variable Types
• IsNumeric(), IsDate() and IsArray()
• Why Declare Variables?
• A Variable's Scope
• A Variable's Lifetime
• Constants in Visual basic 2008
• Arrays in Visual Basic 2008
• Initializing Arrays and Array Limits
• Multidimensional Arrays
• Dynamic Arrays