进制转换及数论练习VB.docx
1、小李编写VB程序，实现如下功能：在文本框Textl中输入一个“十六进制数”(注: 包含小数),例如：在文本框Textl中输入A2.4,单击“转换”按钮Command 1,在标签 Labe 12输出该十六进制对应的十进制数，运行界面如图所示。(1)为实现上述功能，请在划线处填入合适的代码，使程序正常运行。Private Sub Command1 Click()Dim i As Integer, x As String, n As Integer, m As Integer Dim y As Integer, s As Single, r As Stringx 二 Textl.Text: s = 0For i = 1 To nIf Mid(x, i, 1) = . Then Exit For Next i m二i '小数点位置For i = 1 To nr = Mid(x, i, 1)If r >="0 And r二9 Then y = Vai (r)If r >= A And r <= F Then y =(2)If i < m Then s =(3) '整数部分If i > m Then s = s + y * 16 c (m - i)小数部分Next iLabel2. Caption = 对应的十进制数为： + Str (s) + D”End Sub(2)在文本框Textl中输入“A.8”，则在文本框Text2中输出结果是。2、编写“二进制加法”程序。程序运行时，在文本框Textl和文本框Text2分别输入两 个二进制数，单击按钮Commandl后在文本框Text3上输出两个二进制相加后的结果。程 序运行如图所示。观察代码，触发代码执行的事件名是为实现上述功能，请在划线处填入合适的代码。Private Sub Commandl_Click ()Dim bl As String, b2 As String, ans As String, t As StringDim dist As Integer, jw As Integerbl = Textl. Text: b2 = Text2. Text : ans二QIf dist < 0 Thent 二 bl: bl = b2: b2 二 t: dist =-distEnd IfFor i = 1 To distb2 = 0 + b2Next ijw 二 0For i = Len(bl) To 1 Step -1x = Vai (Mid(bl, i, 1) + Vai (Mid(b2, i, 1) + jw ©ans = Str (x Mod 2) + ansNext iIf(3) Then ans = 1 + ansText3.Text = ansEnd Sub 3、编写程序，实现如下功能：在文本框Textl中输入一个整数n, Text2中输入一个整数 x,单击命令按钮Command 1后，将进制n转换为二进制后，将该二进制的后x位在标签Label3显示o比如n=25,转换为二进制后位“H001”，则后4位为“1001” 。程序运行界面如图所示。请补充代码。Private Sub Commandl_Click ()x As IntegerDim i As Integer, n As Integer, Dim r As Integer, s As String ®x = Vai(Text2. Text)x 二 2 八 xn = (2)Do While n > 0r = n Mod 2s = r & sLoop不足x位，前面补0For i = 1 To Vai (Text2. Text) - Len(s)八 Is = 0 + sNext iLabel3. Caption = "n转二进制数的后x位为 + sEnd Sub4、若两个素数之差为2,则该对素数称为双胞胎数，如3、5就是一对双胞胎数。编写VB 程序，实现如下功能：程序运行时，在文本框Textl输入变量n的值，单击按钮Commandl 后，在列表框Listl中显示n以内的所有双胞胎数，程序运行时的界而如图所示。实现上述功能的VB程序如下，请完善代码：Private Sub Commandl Click()Dim flag As BooleanDim n As Integer, i As Integer, k As Integer, num As IntegerQnum 二 0For k = 3 To nflag : TrueFor i = 2 To k - 1If Then flag = FalseEnd IfNext iIf flag = True ThenListl.Additem Str(k) + Str(k + 2) ©End If5双胞后数输入电值：50互算3 55 111 1317 1929 3141 43共6对双胞胎数Next kLabel2. Caption = 共 + Str (num) + 对双胞胎数End Sub5、一个正整数(非素数)可以表示成它的质因子(“1”与其本身除外)的乘积。给出任一 个整数N,求出它所有的质因子以及每个因子出现的次数。例如：整数180=2X2X3X3 X5,所以它的质因子是2,3,5,次数分别是2次，2次，1次。用Visal Basic编写一 个程序求质因子，功能如下：在文本框Textl中输入一个数，单击“计算”命令按Commandl, 在列表框中显示该数的质因子及相应的次数，程序运行时的界面如图所示。实现上述功能的 VB程序如下，请完善代码： Private Sub Command1_Click()5求质因子曰|回通川质因子次数输入一个合数180计算Dim a(l To 100) As Integer '数组a存放该整数的质因子出现的次数 Dim i As Integer, n As Integer, k As Integer Listl. Clear ® k = n 2 For i = 2 To k a(i)= 0 Next i For i = 2 To kDo While n Mod i = 0 n = n i Loop If n = 1 Then Exit For Next i Listl. Addltem 质因子 + For i = 2 To kIf Then Listl. Addltem Str(i) + + Str (a(i) Next iEnd Sub
