题型：综合题 题类：模拟题 难易度：困难
浙江省杭州市五县七校2017届高三上学期期中联考信息技术试题
从被加密字符串中获取单个字符，然后得到其ascii码的8位二进制编码。
将字符的二进制编码反向，得到其逆序二进制码。
将逆序二进制码的每4位转换为相应的十六进制编码，即得到单个字符加密后的字符串。
以此类推，直到所有字符加密完成，得到加密字符串。
具体程序界面如下图，在text1中输入字符串，点击“加密”按钮command1后，在text2中显示加密后的字符串。
程序中②画线处应填入。
Private Sub Command1_Click()
Dim s As String, ch As String
Dim result As String, chA As String, chB As String
Dim i As Integer, j As Integer
Dim n As Integer, m As Integer
s = Text1.Text
n = Len(s)
result = "": c = "0123456789ABCDEF"
For i = 1 To n
ch = ①
ch = niXu(ch)
m = 0
For j = 1 To 4 ' 获取二进制码前4位的值
②
Next
chA = Mid(c, m + 1, 1)
m = 0
For j = 5 To Len(ch)
m = m * 2 + Val(Mid(ch, j, 1))
Next
chB = Mid(c, m + 1, 1)
result = result + chA + chB
Next
Text2.Text = result
End Sub
' 得到单个字符ch的8位二进制编码
Function D2B(ByVal ch As String) As String
Dim s As String
Dim data As Integer, i As Integer
data = Asc(ch)：s = ""
Do While data > 0
s =Str(data Mod 2) + s
data = data \ 2
Loop
If Len(s) < 8 Then
For i = 1 To 8 - Len(s)
s = "0" + s
Next
D2B = s
Else
D2B = s
End If
End Function
' 返回字符串s的逆序
Function niXu(ByVal s As String) As String
Dim i As Integer：Dim r As String
r = ""
For i = Len(s) To 1 Step -1
r = r + Mid(s, i, 1)
Next
niXu = r
End Function
试题篮
