题型:综合题 题类:常考题 难易度:困难
浙江省高一下学期信息技术期末考试试卷
下列Visual Basic程序的功能是将K进制(k<=10)数x转换成十进制数。界面如图所示,在文本框Text1中输入数制k,在文本框Text2中输入数x,单击"转换"按钮(Command1)后,在标签Label4中输出转换的结果。
解决此问题的算法流程图如图所示,相应的Visual Basic程序如下:
Private Sub Command1_Click()
Dim b As Long, i As Integer, k As Integer, x As Long, t As Integer
b = 0: i = 1
k = Val(Text1.Text)
x = Val(Text2.Text)
t = x Mod 10
Do While ①
b = ②
x = x \ 10
t = x Mod 10
i = i + 1
Loop
Label4.Caption = Str(k) + "进制数" + Text2.text + "转换成十制数为" + Str(b)
End Sub
在程序①和②划线处,填入适当的语句或表达式,把程序补充完整:
①将该字符的ASCII码值转化为8位二进制数;
②将后4位二进制数进行按位取反(1变0,0变1);
③将操作②生成的4位二进制数均左移1位(原第1位变为新的第4位);
④原高4位二进制数连接到新的后4位二进制数成为最终加密后字符的内码。
例如:字符“a”经过上述加密运算,可得到字符“m”。
ASCII码值 |
转二进制 |
后四位取反 |
后四位左移 |
拼合 |
转十进制 |
转字符 |
97D |
01100001B |
1110 |
1101 |
01101101B |
109D |
“m” |
程序运行界面如图所示,请改正加框处有误的代码:
Private Sub Command1_Click()
Dim s As String:Dim sl As String:Dim jg As String
Dim n As Integer:Dim x As Integer:Dim i As Integer:Dim j As Integer
Dim a(15)As String
a(0)=“0000”:a(1)=“0001”:a(2)=“0010”:a(3)=“0011”
a(4)=“0100”:a(5)=“0101”:a(6)=“0110”:a(7)=“0111¨
a(8)=“1000”:a(9)=“1001”:a(10)=“1010”:a(11)=“1011¨
a(12)=“1100”:a(13)=“1101”:a(14)“1110”:a(15)=“1111”
jg=“ ”
s=Text1.Text
For i=1 To Len(s)
n=Asc(Mid(s,i,1))
low=n Mod 16
low=15-low ‘执行步骤②
s1=Mid(a(low),2,3)&Mid(a(low),1,1) ‘执行步骤③
For i=l To 4
x=x+Val(Mid(s1,j,1))* ‘⑴{#blank#}1{#/blank#}
Next j
x= *16+x ‘⑵{#blank#}2{#/blank#}
jg=jg&Chr(x)
Next i
Text2.Text=jg
End Sub
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