vb怎么将一个英语句子按字母排序

Private Function paixu(ByVal st As String) As String
Dim i As Integer, temp As Integer, leng As Integer = Len(st), tempst As String = ""
Dim a(leng) As Integer
For i = 1 To leng
a(i) = Asc(Mid(st, i, 1))
Next i
For i = 1 To leng Step 1
For j = 1 To leng - i Step 1
If a(j) > a(j + 1) Then
temp = a(j + 1)
a(j + 1) = a(j)
a(j) = temp
End If
Next j
Next i
For i = 1 To leng
tempst = tempst Convert.ToChar(a(i)).ToString
Next
Return tempst
End Function