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VB.NET Language in a Nutshell, Second Edition by Steven Roman PhD, Paul Lomax, Ron Petrusha

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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

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