Private Sub Form_Click()
Dim i As Integer, y As Single, n As Integer, s As Single
n = InputBox("输入n值", "")

For i = 1 To n
y = (-1) ^ (i - 1)
s = s + y / n
Next i
Print s

与

Private Sub Form_Click()
Dim i As Integer, y As Single, n As Integer, s As Single
n = InputBox("输入n值", "")
s = 1
For i = 2 To n
y = (-1) ^ (i - 1)
s = s + y / n
Next i
Print s
这两个结果为什么会不同呢？请教

以下是引用coachard在2007-9-22 9:58:24的发言：
这就是数学问题了。。。

不过当N取1时，第二个循环跟本动都没动~~~

为什么会这样呢？？

真对不起,那我把列题发上去,看能不能想到??
列:求下列表达式的值
1-1/2+1/3-1/4+....+(-1)^(n-1)*1/n
解答:
Private Sub Form_Click()
Dim i As Integer, y As Single, n As Integer, s As Single
n = InputBox("输入n值", "")
s = 1
For i = 2 To n
y = (-1) ^ (i - 1)
s = s + y / n
Next i
Print s

Private Sub Form_Click()
Dim i As Integer, y As Single, n As Integer, s As Single
n = InputBox("输入n值", "")
For i = 1 To n
y = (-1) ^ (i - 1)
s = s + y / n
Next i
Print s
两者为什么结果不同??
谢谢

后者当N=1时正确,当N>=2后,S=0??

居然出在那个上面,我改了,两者都对了.
感谢大家帮忙!!