用VB编程计算1-2+3-4+5-6…±n的值，n由文本框输入

楼上的程序，个人认为有点小问题，修改如下：

Private Sub Form_Click()
Dim n As Integer
Dim sum As Integer
sum = 0
n = Val(InputBox("输入一个整数："))
sum = 0
For i = 1 To n '此处修改
sum = sum + (-1) ^ (i + 1) * i '此处修改
Next i
Print sum
End Sub

Private Sub Form_Click()
Dim n As Integer
Dim sum As Integer
sum = 0
n = Val(InputBox("输入一个整数："))
For i = 0 To n
sum = sum + (-1) ^ (i - 1) * i
Next i
Print sum
End Sub

Private Sub Form_Click()
Dim i#
i# = InputBox("输入n")
If i# <= 0 Then
MsgBox "输入有误！"
Exit Sub
End If
If ( i# And 1 ) = 0 Then
MsgBox "结果为-1"
Else
MsgBox "结果为1"
End If
End Sub