vba操作excel的合并单元格代码

Sub mergeunit()
Dim spos, epos As Integer
Dim ustr, nowstr As String
spos = 1
epos = 1
ustr = Cells(1, 1)
Application.DisplayAlerts = False

Do
    nowstr = Cells(epos, 1)
    If nowstr <> ustr Then
         Range("A" & spos & ":A" & epos - 1).Select
         With Selection
            .HorizontalAlignment = xlCenter
            .VerticalAlignment = xlCenter
            .WrapText = False
            .Orientation = 0
            .AddIndent = False
            .IndentLevel = 0
            .ShrinkToFit = False
            .ReadingOrder = xlContext
            .MergeCells = True
            ustr = nowstr
        End With
        Selection.Merge

        spos = epos
    End If
    epos = epos + 1
Loop While Len(nowstr) > 0
End Sub