下列VB程序实现数字字母混合序列分离后分别排序，最后又合并输出。具体算法如下：在文本框Text1输入若干组混合序列，每组序列中仅包含一组字母和一个多位数字，序列之间用逗号隔开，以逗号结束。单击“排序”按钮command1，把每组序列中的字母和数字分开，并分别排序，最后在列表框list1输出。排序规则如下：所有数字按从小到大升序排序，字母序列按长度升序排序，若长度相同，直接按字母序列大小升序排序（按字母的ASCII码排序，“A”<“Z”<“a”<“z”）。实现算法的部分程序界面如图所示，VB程序代码如下，回答下列问题：

Private Sub Command1_Click()

Dim a(1 To 6) As Integer, b(1 To 6) As String, i as integer, j as integer

Dim c As String, k As Integer, tmp1 As Integer, tmp2 As String

s=text1.text

i = 1: k = 1: tmp1 = 0: tmp2 = ""

Do While i <= Len(s)

      c = Mid(s, i, 1)

      If c = "," Then

         a(k) = tmp1: b(k) = tmp2

         tmp1 = 0: tmp2 = ""

              ①    

      Else

        If  Then 

           tmp2 = tmp2 + c

        Else

         tmp1=tmp1*10+val(c)

        End If

      End If

      i = i + 1

    Loop

    For i = 1 To 5

      For j = 1 To 6 - i

        If a(j) > a(j + 1) Then tmp1 = a(j): a(j) = a(j + 1): a(j + 1) = tmp1

    If Len(b(j)) > Len(b(j + 1)) Or      ②       Then

          tmp2 = b(j): b(j) = b(j + 1): b(j + 1) = tmp2

        End If

      Next j

    Next i

    For i = 1 To 6

      List1.AddItem Str(a(i)) + b(i)

    Next i

    End Sub