VB.Net Find Missing Numbers in a Sequence

''' <summary>   

''' Returns the missing numbers in a sequence.   

''' </summary>   

''' <param name="strNumbers">Expects a string of comma-delimited numbers. ex: "1,2,4,6,7"</param>   

''' <returns></returns>   

''' <remarks></remarks>   

Public Function FindMissingNumbers(ByVal strNumbers As String) As StringCollection   

  Dim MissingNumbers As New StringCollection   

  Dim arNumbers() As String  

  arNumbers = Split(strNumbers, ",")  

  arNumbers = SortNumbers(arNumbers)  

  For I = 0 To UBound(arNumbers) - 1  

    If CLng(arNumbers(I)) + 1 <> CLng(arNumbers(I + 1)) Then  

      For J = 1 To (CLng(arNumbers(I + 1)) - CLng(arNumbers(I))) - 1  

        MissingNumbers.Add(CStr(CLng(arNumbers(I)) + J))  

      Next  

    End If  

  Next  

  Return MissingNumbers  

End Function  

''' <summary>  

''' Sorts the array of numbers in value order, least to greatest.  

''' </summary>  

''' <param name="arNumbers">Send in a string() array of numbers</param>  

''' <returns></returns>  

''' <remarks></remarks>  

Private Function SortNumbers(ByVal arNumbers() As String) As String()  

  Dim tmpNumber As String  

  For J = 0 To UBound(arNumbers) - 1  

    For I = J + 1 To UBound(arNumbers)  

      If arNumbers(I) - arNumbers(J) < 0 Then  

        tmpNumber = arNumbers(J)  

        arNumbers(J) = arNumbers(J)  

        arNumbers(I) = tmpNumber  

      End If  

    Next  

  Next  

  Return arNumbers  

End Function