CST2601 Visual Basic I
Notes on LBound and UBound

LBound Function

Returns a Long containing the smallest available subscript for the indicated dimension of an array.

Syntax

LBound(arrayname[, dimension])

The LBound function syntax has these parts:

Part Description
arrayname Required. Name of the array variable; follows standard variable naming conventions.
dimension Optional; Variant (Long). Whole number indicating which dimension's lower bound is returned. Use 1 for the first dimension, 2 for the second, and so on. If dimension is omitted, 1 is assumed.
 

Remarks

The LBound function is used with the UBound function to determine the size of an array. Use the UBound function to find the upper limit of an array dimension.

LBound returns the values in the following table for an array with the following dimensions:

Dim A(1 To 100, 0 To 3, -3 To 4)
Statement Return Value
LBound(A, 1) 1
LBound(A, 2) 0
LBound(A, 3) -3
 

The default lower bound for any dimension is either 0 or 1, depending on the setting of the Option Base statement. The base of an array created with the Array function is zero; it is unaffected by Option Base.

Arrays for which dimensions are set using the To clause in a Dim, Private, Public, ReDim, or Static statement can have any integer value as a lower bound.

LBound Function Example

This example uses the LBound function to determine the smallest available subscript for the indicated dimension of an array. Use the Option Base statement to override the default base array subscript value of 0.

Dim Lower
Dim MyArray(1 To 10, 5 To 15, 10 To 20)    ' Declare array variables.
Dim AnyArray(10)
Lower = Lbound(MyArray, 1)    ' Returns 1.
Lower = Lbound(MyArray, 3)   ' Returns 10.
Lower = Lbound(AnyArray)   ' Returns 0 or 1, depending on
   ' setting of Option Base.

UBound Function

Returns a Long containing the largest available subscript for the indicated dimension of an array.

Syntax

UBound(arrayname[, dimension])

The UBound function syntax has these parts:

Part Description
arrayname Required. Name of the array variable; follows standard variable naming conventions.
dimension Optional; Variant (Long). Whole number indicating which dimension's upper bound is returned. Use 1 for the first dimension, 2 for the second, and so on. If dimension is omitted, 1 is assumed.
 

Remarks

The UBound function is used with the LBound function to determine the size of an array. Use the LBound function to find the lower limit of an array dimension.

UBound returns the following values for an array with these dimensions:

Dim A(1 To 100, 0 To 3, -3 To 4)
Statement Return Value
UBound(A, 1) 100
UBound(A, 2) 3
UBound(A, 3) 4
 

UBound Function Example

This example uses the UBound function to determine the largest available subscript for the indicated dimension of an array.

Dim Upper
Dim MyArray(1 To 10, 5 To 15, 10 To 20)   ' Declare array variables.
Dim AnyArray(10)
Upper = UBound(MyArray, 1)   ' Returns 10.
Upper = UBound(MyArray, 3)   ' Returns 20.
Upper = UBound(AnyArray)   ' Returns 10.