Validating user input excel vba - vba

Question

I have the following user input set up in excel vba. The function when called asks the user to input a single number no greater than 9999, or two numbers in the format XXXX-XXXX where two numbers are separated by a dash. In that case, the numbers cannot be greater than 9999 in either case, or at least shouldn't.
The goal is to return either a single number (IE 50) or a range (IE low value is 50,high value is 75). Currently as set up it should be returning an array, where the first position is the low value, and the second position is high value. Or, if the user only enters one number, it should return that one number in the first position of an array.
Currently it checks that A) user has entered in a number, B) the number is not greater than 4 digits long.
Unfortunately it is not returning an array, it is returning an error. Subscript out of range.
Also, are there any other likely user inputs that should be checked for here? The application is not going to be widely used by people, but I'd like to minimize potential errors as well.
Public Function getUserInput() As Variant
'this function gets a user input from an input box and puts it out into the proper format
Dim inputString As String
Dim numArr() As String
Dim i As Long
' On Error GoTo NotValidInput
inputString = Trim(InputBox("Enter the rows you'd like to print"))
'has the user entered a dash into their user input
If InStr(inputString, "-") > 0 Then
numArr() = Split(inputString, "-")
If UBound(numArr) <> 1 Then
GoTo NotValidNumberFormat
End If
If (IsNumeric(numArr(0)) And Len(numArr(0)) <= 4) And (IsNumeric(numArr(1)) And Len(numArr(1)) <= 4) Then
getUserInput = numArr
Exit Function
Else
GoTo NotValidNumberFormat
End If
'no dash
'60
Else
If (IsNumeric(CInt(inputString))) And Len(inputString) <= 4 Then
getUserInput = numArr
Exit Function
Else
GoTo NotValidNumberFormat
End If
End If
Exit Function
NotValidNumberFormat:
'if the conversion failed, return error
MsgBox ("Please enter the number in a valid format - either a single number no larger than 9999 or two numbers no larger than 9999 separated by only one dash (IE XX-XX)")
getUserInput = -1
End Function

Answer 1

this should do:
Public Function getUserInput() As Variant
'this function gets a user input from an input box and puts it out into the proper format
Dim numArr As Variant
Dim goOn As Boolean
Do
numArr = Split(WorksheetFunction.Trim(InputBox("Enter the rows you'd like to print in the format 'nnnn' or 'nnnn-mmmm'")), "-")
Select Case UBound(numArr)
Case 0
goOn = Format(numArr(0), "0000") Like "####"
Case 1
goOn = Format(numArr(0), "0000") Like "####" And Format(numArr(1), "0000") Like "####"
End Select
If Not goOn Then MsgBox "Please enter the number in a valid format - either a single number no larger than 9999 or two numbers no larger than 9999 separated by only one dash (ex: XX-XX)"
Loop While Not goOn
getUserInput = numArr
End Function