Understanding Data Types

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	Special Edition Using Microsoft® Visual Basic® .NET By Brian Siler, Jeff Spotts
	Table of Contents
	Chapter 6.  Storing Information in Variables

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Okay, you know what a variable does and how to name it. But what can you store in a variable? The simple answer is: almost anything. A variable can hold a numeric value; a string of text; or a reference to an object, such as a form, control, or database. This chapter looks specifically at using variables to store numbers, strings, and dates. Table 6.2 lists Visual Basic's data types:

Table 6.2. Visual Basic Data Types

Visual Basic .NET Data Type	Values Stored	Example	Memory Requirements
Boolean	True/False	True	2 bytes
Byte	0 255	122	1 byte
Char	Single Character	A	2 bytes
Date	Dates and Times	12/21/1970 02:00 PM	8 bytes
Decimal	Decimal or Whole	19.95D	16 bytes
Double	Decimal Numbers	1.23E-10	8 bytes
Integer	Whole Numbers	8675309	4 bytes
Long	Whole Numbers	19-digit number	8 bytes
Object	A reference to an object of any type		4 bytes
Short	Whole Numbers	32,123	2 bytes
Single	Decimal Numbers	.0000123	4 bytes
String	Characters	HELLO	Depends on length

Note

The little Integer from VB 6.0 has finally grown up! A Visual Basic .NET Integer variable can store the entire range of values of a Visual Basic 6.0 Long variable. (This brings a welcome level of consistency to those programmers who work with the int type in SQL databases.) A new type, the Short type, takes the place of the VB6 Integer with a range of -32,768 to +32,767.

Note

The Currency data type from earlier versions of Visual Basic has been eliminated. The help files suggest using the new Decimal data type as a replacement.

Note

The Variant data type, capable of storing any other variable type, has been eliminated. Because all of the base data types derive from the Object class, Microsoft has named Object as the new universal data type.

In Visual Basic .NET, even the most basic data types act like objects, with their own properties and methods. When you type a variable name in the Code Editor and press the period key, you will see all the associated methods and properties.

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