VB.NET Language in a Nutshell, Second Edition

Name

ReDim Statement

Syntax

ReDim [Preserve] varname(subscripts) _
                 [, varname(subscripts)  ...

Preserve (optional; Keyword)

Preserves the data within an array when changing the only or last dimension

varname (required; String literal)

Name of the variable

subscripts (required; Numeric)

Number of elements and dimensions of the array, using the syntax:

                           upper [, upper] ...

The number of upper bounds specified is the number of dimensions. Each upper bound specifies the size of the corresponding coordinate.

Description

Used within a procedure to resize and reallocate storage space for an array

Rules at a Glance

• Arrays can be sized or resized using the ReDim statement. There is no limit to the number of times you can redimension a dynamic array.

• The dimension cannot be changed, nor can the data type of the array be changed.

• If you do not use the Preserve keyword in redimensioning the array, you can resize any of the coordinates of the array.

• Use of the Preserve keyword allows you to retain the current values within the array, but it also allows you to resize only the last coordinate of an array.

• You can redimension an array in a called procedure if you pass the array to the procedure by reference. For example:

  Public Sub Main Dim lArr( ) AS Object = {1,2,3,4,5,6,7,8,9,10} Dim lNum As Long ResizeArray(lArr) for each lNum in lARr Console.WriteLine(lNum) Next End Sub Public Sub ResizeArray(ByRef arr( ) As Object) ReDim Preserve arr(15) arr(10) = 20 arr(11) = 50 arr(12) = 80 arr(13) = 90 arr(14) ...