Question

vb for..next循环求和问题！

Private Sub Command2_Click()
Dim i As Integer, sum As Integer
sum = 0
For i = 100 To 1 Step -1
sum = sum + i
i = i - 1
Next i
Print sum
End Sub
结果：2550

Private Sub Form_Click()
Dim i As Integer, sum As Integer
sum = 0
For i = 1 To 100 Step 1
sum = sum + i
i = i + 1
Next i
Print sum
End Sub

结果：2500

这两个为什么还不一样？我是哪里出错了？求指导！

Answer 1

解：
1.在command1_click中求的是100以内的偶数和，而在form_click中求的是100以内的奇数和，所以这两个的结果就不一样了
2.要使form_click中的结果与command1_click中的结果一样则：
Private Sub Form_Click()
Dim i As Integer, sum As Integer
sum = 0
For i = 1 To 100 Step 1
i = i + 1
sum = sum + i
Next i
Print sum
End Sub
3.要使command1_click中的结果与form_click中的一样则：
Private Sub Command2_Click()
Dim i As Integer, sum As Integer
sum = 0
For i = 100 To 1 Step -1
i = i - 1
sum = sum + i
Next i
Print sum
End Sub

Answer 2

for循环自身带有累加计算，不要再添加i=i+1了，和i=i-1.都去掉就可以了
如果可以请采纳。

Answer 3

For i = 100 To 1 Step -1
前一个从100 到2的偶数相加
For i = 1 To 100 Step 1
这个从1 到99 的奇数相加

Answer 4

第一个计算过程是
100
100+98
100+98+96
...
第二个计算过程是
1
1+3
1+3+5
...