Visual Basic 2005 in a Nutshell, Third Edition

Collections | 67

Variables and

Data Types

This is the Title of the Book, eMatter Edition

Copyright © 2006 O’Reilly & Associates, Inc. All rights reserved.

Array declarations can:

• Call the array’s constructor implicitly or explicitly

• Specify an initial size for each dimension or leave the initial size unspecified

• Initialize the elements of the array or not

In VB 6, the programmer could specify both the lower and upper bounds of any

array dimension. With .NET, all Visual Basic arrays have a lower bound of zero.

The statement:

Dim myArray(5) As Integer

declares an array with six elements, numbered zero through five.

Arrays can include multiple dimensions. The following example declares and

initializes a two-dimensional array:

Dim rectArray(,) As Integer = {{1, 2, 3}, {4, 5, 6}}

The following code displays the contents of this array:

Debug.Write(rectArray(0, 0))

Debug.Write(rectArray(0, 1))

Debug.WriteLine(rectArray(0, 2))

Debug.Write(rectArray(1, 0))

Debug.Write(rectArray(1, 1))

Debug.WriteLine(rectArray(1, 2))

' ----- The output is:

123

456

The upper bound of any array dimension can be modified using the ReDim

statement.

ReDim [Preserve] arrayName(newUpperBound)

The Preserve qualifier retains any existing values in the array; all array elements

are cleared in the absence of this qualifier. When using

Preserve, only the last

dimension of an array can have its upper bound modified. The number of dimen-

sions ...