Dim sum As Integer    'sum 用来统计符合条件的自然数个数'

Dim n, max As Integer

List1.Clear

sum = 0

max = {#blank#}1{#/blank#}'指定查找范围的最大自然数，Text1文本框中输入'

n = 0

Do While n <= max

  n = n + 1            '从自然数1开始不断往上寻找'

  If {#blank#}2{#/blank#}Then

  List1.AddItem Str(n) '找到后在List1中显示结果'

  {#blank#}3{#/blank#}

  End If

Loop

List1.AddItem ("共计" + Str(sum) + "个")

End Sub

程序代码如下：

Private Sub Command1_Click()

  Dim i As Integer

  List1.Clear  '清除列表框内容

End Sub

Private Function f(x As Integer) As Boolean  '判断是否为素数，若是返回true,若不是则返回false

………

End Function

密码强度判断条件如下：密码长度小于6，则强度为“弱”。在密码长度大于等于 6 的情况下，若只出现一种字符，则密码强度为“弱”；若出现两种不同字符，则密码强度为“中”，出现3种以上不同字符，则密码强度为“强”。

为实现上述功能程序如下，但加框处的代码有误，请改正。

Private Sub Command1_Click()

    Dim n As Integer

    Dim i As Integer, c As Integer

    n = Val(Text1.Text)

    List1.Clear

    c = 0

    If n Mod 2 = 0 Then

        For        ①

            If    Then            ②

                List1.AddItem n & "=" & i & "+" & n - i

                c = c + 1

            End If

        Next i

        Label2.Caption = "共有" & c & "种组合"

    Else

        Label2.Caption = "请输入一个大于 2 的偶数"

    End If

End Sub

Function is Prime(x As Integer) As Boolean

    Dim i As Integer

    Is Prime = True

    For i = 2 To Int(Sqr(x))

        If x Mod i = 0 Then

            Is Prime = False

            Exit For

        End If

    Next i

End Function

①{#blank#}1{#/blank#} ②{#blank#}2{#/blank#} 

Dim a(1 To 1000) As Integer

Dim n As Integer

Private Sub Form_Load()

'确定n的值和数组a的各个元素值，即每根棍子的长度值，代码略

End Sub

Function max (x As Integer, y As Integer) As Integer

    If x>y Then

        max=x

    Else

        max=y

    End If

End Function

Private Sub Command1_Click()

    Dim i As Integer, J As Integer, K As Integer

    Dim ans As Integer, c As Integer, longest As Integer,

    rest As Integer

    ans=0

    '让i<j<k，保证棍子不会被重复选中

    For i=1 To n

        For j=i+1 To n

            For k=j+1 To n

                c=a(i)+a(j)+a(k)

                longest=      '①

                rest=c-longest        'rest 保存最短的两条边的和

                If Then      '②

                    ans=max(ans, c)

                End If

            Next k

        Next j

    Next i

    Print ans

End Sub