VB程序如下,请回答以下问题:
Private Sub Command1_Click()
Dim s As String, ch As String
Dim i As Integer
Dim r As Integer, result As Integer
Dim flag As Boolean
s = Text1.Text
i = 1:result = 0:flag = True
Do While
ch = Mid(s, i, 1)
r = ①
If r > 9 Or r < 0 Then
flag = False
Else
②
End If
i = i + 1
Loop
Text2.Text = Str(result)
End Sub
① ②