怎么用VB来求Y=1-1/2+1/3-1/4+1/5-1…前30项之和。

s1=0
s2=0
for i=1 to 30 step 2
s1=s1+1/i
s2=s2+1/(1+i)
next
y=s1-s2

For i = 1 To 30
If i Mod 2 = 0 Then
s = s - 1 / i
Else
s = s + 1 / i
End If
Next i
Print s

楼上的都做出来了，我用另外方法 做个，仅供参考
Dim i As integer, Y As single, k As Integer, m As single
k = 1
Y = 0
m = 1
For i = 1 To 30
m = 1 / i
Y = Y + k * m
k = -k
Next
Print "Y值 "; Y