①密码是六位数字，前面两位为59；

②最后两位数字相同；

③能被12和38整除。

程序界面如1图所示，单击 “帮助找回密码”按钮（Command1）后，可能的密码显示在列表框List1中。

实现上述功能的VB代码如下, 但划线处代码有错，请改正。

Dim a(1 To 50) As Integer

Private Sub Command1_Click()

Dim i As Integer

k = 0: i = 3

Do While i <= 100

   If  ① prime(i)   Then      ‘⑴

      k = k + 1

      a(k) = i

   End If  

   i = i + 2

Loop

For i = 2 To k

   If   ②a(i) = a(i +1)+2   Then   ‘⑵

      List1.AddItem Str(a(i - 1)) + "和" + Str(a(i))

   End If

Next i

End Sub

Function prime(x As Integer) As Boolean

prime = False

For i = 2 To Int(Sqr(x))

   If  x Mod i = 0  Then

      prime = True

      Exit For

   End If

Next i

End Function

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

实现上述功能的VB代码如下：

Private Sub Command1_Click() Dim a(0 To 4) As String Dim b(0 To 4) As Integer

Dim s As String, r As String

Dim i As Integer, j As Integer, k As Integer, c As Integer, n As Integer

List1.Clear

s = Text1.Text :   n = Len(s)

If         Then    '选填 Label1.Caption = "数据输入有误！"

Exit Sub   '退出 End If

For i = 0 To n - 1

a(i) = Mid(s, i + 1, 1) b(i) = 0

Next i c = 0

For i = 1 To n ^ n r = ""

For j = 0 To n - 1

Next j

c = c + 1 List1.AddItem r k = 0

b(k) = b(k) + 1

Do While b(k) = n And k < 4 b(k) = 0

b(k) = b(k) + 1 Loop

Next i

Label1.Caption = "构造字符串的方法共计" + Str(c) + "种。" End Sub

Function test(s As String) As Boolean ‘用于判别是否存在重复的字符，代码略

‘若无重复，则返回True，否则返回False

End Function

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