设有下面程序代码： Private Sub Command1_Click() Dim str As String, ch As String str = "Visual Basic Programming" ch = "a" n = fun(ch, str) Print str, n End Sub Private Function fun(ch As String, str As String) As Integer Dim strbuf As String, c As String, n As Integer For k = 1 To Len(str) c = Mid$(str, k, 1) If c <> ch Then strbuf = strbuf & c Else strbuf = strbuf & UCase(c) n = n + 1 End If Next k str = strbuf fun = n End Function 程序运行时的输出是