VB.NET Language in a Nutshell, Second Edition

Name

UBound Function

Class

Microsoft.VisualBasic.Information

Syntax

UBound(array[, rank])

array (required; any)

The name of the array

rank (optional; Integer)

A number specifying the dimension of the array

Return Value

Integer

Description

Indicates the upper limit of a specified coordinate of an array. The upper boundary is the largest subscript you can use with that coordinate.

Rules at a Glance

• To determine the upper limit of the first coordinate of an array, set rank to 1, set it to 2 for the second coordinate, and so on.

• If rank is not specified, 1 is assumed.

• The function returns -1 if the array is uninitialized.

Programming Tips and Gotchas

• Note that UBound returns the actual subscript of the upper bound of a particular array dimension.

• The number of valid indices for the ith coordinate is equal to UBound(array, i) + 1.

• If array is an uninitialized array, passing it to the UBound function generates an ArgumentNullException exception. To prevent this, you can declare the array as follows:

  Dim arrValues(-1) As String