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请统计某个给定范围[L, R]的所有整数中,数字2出现的次数。比如给定范围为[2, 22],数字2在数2 中出现了1次,在数12中出现1次,在数20中出现1次,在数21中出现1次,在数22中出现2次,所以数字2 在该范围内一共出现了6次。 小明编写如下图所示VB应用程序,在文本框Text1中输入区间左边界,在文本框Text2中输入区间右边 界,单击“统计数字”按钮Command1后,在标签框Label1中输出给定区间内所有整数中出现“2”的次 数。

(1)要使程序运行时,窗体Form1标题显示“统计数字”,则需在Form_Load事件过程中添加语句________
(单选,填字母:
A.Form1.Text="统计数字"/B.Form1.Caption="统计数字"/C.Form1.AddItem "统计数字")
(2)实现上述功能的VB程序如下,请在划线处填入合适代码。
Private Sub Command1_Click()
Dim left As Integer, right As Integer, s As String
Dim i As Integer, j As Integer, k As Integer, ch As String left = Val(Text1.Text)
right = Val(Text2.Text)
s = ""
k = 0
①________
Do While i <= right
s = s + Str(i)
i = i + 1
Loop
For i = 1 To Len(s)
ch = Mid(s, i, 1)
If ch = "2" Then ②_____ 
Next i
Label1.Caption = Str(left) + "到" + Str(right) + "之间出现2的次数为" + Str(k) End Sub
(3)若在文本框Text1中输入300,在Text2中输入400,单击“统计数字”按钮后,标签Label1中显示的 内容是________。
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同类题5

曲哲同学设计了一个英文字符串的加密算法,其加密的方法如下:
1.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。
2.将字符的二进制编码反向,得到其逆序二进制码。
3.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。
4.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。
(1)已知字符a的ascii码为97,则字符串idear加密后的字符串为____________________。
(2)阅读整段程序,程序中①画线处应填入
程序中②画线处应填入     。:学+科+网

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 =  
ch = niXu(ch)
m = 0
For j =" 1" To 4  ' 获取二进制码前4位的值

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