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Learning Visual Basic .NET by Jesse Liberty

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Chapter 5. VB.NET Language Fundamentals

Chapter 2 demonstrates a very simple VB.NET program that prints the text string "Hello world!" to the console screen and provides a line-by-line analysis of that program. However, even that very simple program was complex enough that some of the details had to be skipped over. The current chapter begins an in-depth exploration of the syntax and structure of the VB.NET language.

Types

Every object you create or use in a VB.NET program must have a specific type (e.g., you must declare the object to be an integer or a string or a Dog or a Button). The type tells the compiler how big the object is and what it can do.

Types come in two flavors: those that are built into the language (intrinsic types) and types you create (classes, structs, and interfaces, discussed in Chapter 8, Chapter 12, and Chapter 13, respectively). VB.NET offers a number of intrinsic types, shown in Table 5-1.

Table 5-1. The intrinsic types

Type

Size (in bytes)

.NET type

Description

Boolean

1

Boolean

True or false.

Byte

1

Byte

Unsigned (values 0-255).

Char

2

Char

Unicode characters.

Date

8

DateTime

Midnight 1/1/0001 through 11:59:59 12/31/9999.

Decimal

12

Decimal

Fixed-precision numbers up to 28 digits and the position of the decimal point; typically used in financial calculations; requires the suffix "m" or "M."

Double

8

Double

Double-precision floating-point numbers; holds the values from approximately +/-5.0 * 10-324 to approximately ...

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