Private Sub Command1_Click()

    Dim s As String, ch As String

Dim fh As Integer, p As Integer, sum As Integer

s = Text1.Text: fh = 1: p = 0: sum = 0

    For i = 1 To Len(s)

        ch = Mid(s, i, 1)

        If              ①                Then   '判断取出的字符是否为数字

p = p * 10 + Val(ch)

        Else

            sum = sum + p * fh

            p = 0

            If ch = "-" Then

                        ②        

            ElseIf ch = "+" Then

                fh = 1

            End If

        End If

    Next i

    Label3.Caption = Str(sum)

    List1.AddItem                  ③             

End Sub

① ② ③