3道简单的VB编程题目，谢谢帮忙
LZ的三个简单问题代码如下，未详细设计，仅供参考：
具体是在工程的form1窗体中添加三个命令按钮，其它属性默认即可，将下面的代码拷贝过去并运行即可。
Private Sub Command1_Click(Index As Integer)
'输出1-1/2+1/3-1/4+。 。。 +1/99-1/100 的和
Dim i As Double
Dim sum As Double
sum = 0
For i = 1 To 100
If i Mod 2 Then
sum = sum + 1 / i
Else
sum = sum - 1 / i
End If
Next
MsgBox sum...全部
LZ的三个简单问题代码如下，未详细设计，仅供参考：
具体是在工程的form1窗体中添加三个命令按钮，其它属性默认即可，将下面的代码拷贝过去并运行即可。
Private Sub Command1_Click(Index As Integer)
'输出1-1/2+1/3-1/4+。
。。
+1/99-1/100 的和
Dim i As Double
Dim sum As Double
sum = 0
For i = 1 To 100
If i Mod 2 Then
sum = sum + 1 / i
Else
sum = sum - 1 / i
End If
Next
MsgBox sum
End Sub
Private Sub Command2_Click()
Dim val As String
val = InputBox("请输入一个整数:", "判断是否素数")
If val = "" Then Exit Sub
MsgBox analyse(CLng(val))
End Sub
Function analyse(val As Long)
Dim i As Long
For i = 2 To val - 1
If val Mod i = 0 Then
analyse = 0
Exit Function
End If
Next
analyse = 1
End Function
Private Sub Command3_Click()
Dim str As String, temp As String
Dim p As Long, i As Long, j As Long, k As Long
i = 0
j = 0
k = 0
str = InputBox("请输入一个字符串:", "统计分析串")
If str = "" Then Exit Sub
For i = 1 To Len(str)
temp = Mid(str, i, 1)
If IsNumeric(temp) Then
i = i + 1
ElseIf (Asc(temp) >= Asc("A") And Asc(temp) = Asc("a") And Asc(temp) <= Asc("z")) Then
j = j + 1
Else
k = k + 1
End If
Next
MsgBox "数字：" & CStr(i) & " 字母：" & CStr(j) & "其它：" & CStr(k) '输出统计结果
MsgBox StrReverse(str) '反序输出
End Sub
。收起
