2008春VB上机试卷VB06答案

2008年（春）上机 Visual Basic（VB06）答案

一、改错

【题目】本程序的功能如下图所示，将输入的一个由数字字符组成的字符串，从第一位、第二位……直到倒数第二位，依次取两位数据，得到一组两位整数输出到列表框1，再将其中的素数挑选出来输出到列表框2（注意，如果截取到的两位数字，第一位为0，例如05，则无效，将其丢弃）。

Option Explicit

Private Sub Command1_Click()

Dim st As String, num() As Integer

Dim k As Integer, i As Integer

st = Text1

i = 1: k = 1

Do

If Mid(st, i, 1) <> "0" Then

ReDim Preserve num(k) 'err 无Preserve

num(k) = Val(Mid(st, i, 2))

List1.AddItem num(k)

k = k + 1

End If

i = i + 1

Loop While i < Len(st) 'err i <= Len(st)

For i = 1 To UBound(num)

If prime(num(i)) Then List2.AddItem num(i)

Next i

End Sub

Private Function prime(n As Integer) As Boolean

Dim i As Integer

For i = 2 To Sqr(n)

If n Mod i = 0 Then Exit Function 'err Exit For

Next i

prime = True

End Function

二、编程题

【题目】编写程序，将 10～5000之间的一组数据，变换到（0, 1）区间。变换的方法是，找出这组数据中的最大数，用大于它的第一个能被100整除的数n ，分别除以这组数据中的每个数。例如，在下图数据中最大数为4810，则n为4900，用所有数据除以4900进行变换。

Option Explicit

Option Base 1

Dim a(20) As Integer

Private Sub Command1_Click()

Dim i As Integer, j As Integer

For i = 1 To 20

a(i) = Int(Rnd * (4999 - 10 + 1)) + 10

Text1.Text = Text1 & Str(a(i))

If i Mod 5 = 0 Then Text1.Text = Text1 & vbCrLf Next i

End Sub

Private Sub Command2_Click()

Dim i As Integer, n As Integer

n = ((maxv \ 100) + 1) * 100

For i = 1 To 20

List1.AddItem a(i) & "---" & CSng(a(i) / n) Next i

End Sub

Private Function maxv() As Integer

Dim i As Integer

maxv = a(1)

For i = 2 To 20

If maxv < a(i) Then maxv = a(i)

Next i

End Function

Private Sub Command3_Click()

Text1.Text = ""

List1.Clear

Command1.SetFocus

End Sub