练习题参考答案.docx

1、练习题参考答案附录练习题参考答案练 习 题 11. 答：略。2. 答：略。练 习 题 21. 答：略。2. 答：略。3. 答：略。练 习 题 3图A.1 Form1设计界面1. 解：Form1窗体的界面如图A.1所示，有两个标签（Label1和Label2）、两个文本框（TextBox1和TextBox2）和一个命令按钮Button1。在该窗体上设计如下代码：Public Class Form1 Private Sub Button1_Click(ByVal sender As System.Object, _ ByVal e As System.EventArgs) Handles Butt

2、on1.Click Dim n As Integer Dim s As Long n = 0 s = Val(TextBox1.Text) Do While s 0 n = n + s Mod 10 s = Int(s * 1.0 / 10) Loop TextBox2.Text = n End SubEnd Class图A.2 Form1执行界面图A.3 Form2设计界面运行本窗体，在TextBox1中输入123456789，单击“求数字和”命令按钮，其结果如图A.2所示。2. 解：Form2窗体的界面如图A.3所示，有3个标签（Label1、Label2和Label3）、两个文本框（Te

3、xtBox1和TextBox2）和一个命令按钮Button1。在该窗体上设计如下代码：Public Class Form2 Private Sub Button1_Click(ByVal sender As System.Object, _ ByVal e As System.EventArgs) Handles Button1.Click Dim y, m, d As Integer Dim leap As Boolean y = Val(TextBox1.Text) m = Val(TextBox2.Text) If y Mod 400 = 0 Then 闰年时leap=true,平年时l

4、eap=false leap = True ElseIf y Mod 4 = 0 And y Mod 100 0 Then leap = True Else leap = False End If Select Case m图A.4 Form2执行界面图A.5 Form3设计界面 Case 1, 3, 5, 7, 8, 10, 12 d = 31 Case 4, 6, 9, 11 d = 30 Case 2 If leap = True Then d = 29 Else d = 28 End If End Select Label3.Text = 该月有 + Trim(Str(d) + 天 E

5、nd SubEnd Class运行本窗体，在TextBox1中输入2009，在TextBox2中输入2，单击“确定”命令按钮，其结果如图A.4所示。3. 解：Form3窗体的界面如图A.5所示，有3个标签（Label1、Label2和Label3）、两个文本框（TextBox1和TextBox2）和一个命令按钮Button1。在该窗体上设计如下代码：Public Class Form3 Private Sub Button1_Click(ByVal sender As System.Object, _ ByVal e As System.EventArgs) Handles Button1.C

6、lick Dim n, m, i As Integer Dim f As Boolean n = Val(TextBox1.Text) m = Val(TextBox2.Text) f = True For i = 0 To n 2 If 2 * i + 4 * (n - i) = m Then Label3.Text = 鸡 + Trim(Str(i) + 只,兔 + _ Trim(Str(n - i) + 只 f = False Exit For图A.6 Form3执行界面 End If Next i If f = True Then Label3.Text = 数据输入错误,无解 End

7、 If End SubEnd Class运行本窗体，在TextBox1中输入30，在TextBox2中输入90，单击“确定”命令按钮，其结果如图A.6所示。练 习 题 4图A.7 Form1设计界面1. 解：Form1窗体的界面如图A.7所示，有两个标签（Label1和Label2）、两个文本框（TextBox1和TextBox2）和一个命令按钮Button1。在该窗体上设计如下代码：Public Class Form1 Private Sub Button1_Click(ByVal sender As System.Object, _ ByVal e As System.EventArgs)

8、 Handles Button1.Click Dim city() As String = 北京, 上海, 天津, 广州, 哈尔滨, _ 长春, 沈阳, 西安, 兰州, 银川, 太原, 济南, 南京, _ 合肥, 郑州, 成都, 重庆, 贵阳, 昆明, 杭州, 福州, _ 南昌, 武汉, 长沙, 南宁, 拉萨, 海口 Dim no() As String = 010, 021, 022, 020, 0451, 0431,_ 024, 029, 0931, 0971, 0951, 0351, 025, 0551,_ 0371, 028, 023, 0851, 0871, 0571, 0591,

9、0791,_ 027, 0731, 0771, 0891, 0898 Dim i As Integer = 0 While (i UBound(no) And StrComp(TextBox1.Text, no(i) 0) i = i + 1 End While图A.8 Form1执行界面图A.9 Form2设计界面 If i score(n) Then score(n + 1) = score(n + 1) + 1 Next I For i = 0 To n - 1 mystr = mystr + Str(score(i) + Chr(13) + Chr(10) Next TextBox2.

10、Text = mystr TextBox3.Text = score(n) TextBox4.Text = score(n + 1) End Sub Private Sub Form4_Load(ByVal sender As System.Object, _ ByVal e As System.EventArgs) Handles MyBase.Load TextBox1.Text = TextBox2.Text = 图A.14 Form4执行界面 TextBox3.Text = TextBox4.Text = End SubEnd Class上述代码中，用score（0n-1）数组元素存放

11、n个学生的分数，score（n）数组元素存放平均分，score（n+1）数组元素存放高于平均分的人数。运行本窗体，输入n为10，单击“确定”命令按钮，结果如图A.14所示。练 习 题 5图A.15 Form1设计界面1. 答：略。2. 答：略。3. 解：Form1窗体的界面如图A.15所示，有两个标签（Label1和Label2）、两个文本框（TextBox1和TextBox2）和两个命令按钮（Button1和Button2）。在该窗体上设计如下代码：Public Class Form1 Private a(9) As Single Private Sub Button1_Click(ByVa

12、l sender As System.Object, _ ByVal e As System.EventArgs) Handles Button1.Click Dim i As Integer Randomize() 随机数初始化 TextBox1.Text = For i = 0 To 9 用随机函数为实参数组元素赋值 a(i) = Int(90 * Rnd() + 10) TextBox1.Text = TextBox1.Text + CStr(a(i) + Next End Sub Private Sub Button2_Click(ByVal sender As System.Obje

13、ct, _ ByVal e As System.EventArgs) Handles Button2.Click Call Aver(a) 调用通用过程,通过形参a返回数组a各元素平均值 TextBox2.Text = Format(a(UBound(a) 显示一维数组的最后一个元素值 End Sub Private Sub Aver(ByRef b() As Single) Dim i, n As Integer n = UBound(a) ReDim Preserve b(n + 1) 重新定义数组的大小,并保持原来的值. b(n + 1) = 0 给最后一个元素赋初值 For i = 0

14、 To n b(n + 1) = b(n + 1) + b(i) Next i图A.16 Form1运行界面图A.17 Form2设计界面 b(n + 1) = b(n + 1) / n 最后一个元素值除以原来的长度得到平均值 End SubEnd Class运行本窗体，分别单击“产生数组”和“求平均值”命令按钮，结果如图A.16所示。4. 解：Form2窗体的界面如图A.17所示，有一个标签（Label1）、3个文本框（TextBox1TextBox3）和两个命令按钮（Button1和Button2）。在该窗体上设计如下代码：Public Class Form2 Dim mm As Inte

15、ger = 7 Function addmm(ByVal x As String) As String 加密操作函数过程 Dim i, n As Integer Dim s1 As String, s2 As String, s3 As String s3 = n = Len(x) For i = 1 To n s1 = Mid(x, i, 1) s2 = Chr(Asc(s1) + mm) s3 = s3 & s2 Next addmm = s3 End Function Function removemm(ByVal x As String) As String 解密操作函数过程 Dim

16、i, n As Integer Dim s1 As String, s2 As String, s3 As String s3 = n = Len(x) For i = 1 To n s1 = Mid(x, i, 1) s2 = Chr(Asc(s1) - mm) s3 = s3 & s2 Next removemm = s3 End Function Private Sub Button1_Click(ByVal sender As System.Object, _ ByVal e As System.EventArgs) Handles Button1.Click Dim s As Str

17、ing = TextBox1.Text TextBox2.Text = addmm(s) End Sub Private Sub Button2_Click(ByVal sender As System.Object, _ ByVal e As System.EventArgs) Handles Button2.Click Dim s As String = TextBox2.Text TextBox3.Text = removemm(s) End Sub Private Sub Form2_Load(ByVal sender As System.Object, _ ByVal e As Sy

18、stem.EventArgs) Handles MyBase.Load图A.18 Form2运行界面图A.19 Form3设计界面 TextBox1.Text = TextBox2.Text = TextBox3.Text = End SubEnd Class上述代码中，运行本窗体，mm为加密因子，addmm是加密操作函数，removemm是解密操作函数，它们分别对原字符串中每个字符的ASCII码加上mm和减去mm。运行本窗体，输入原字符串，分别单击两个命令按钮，结果如图A.18所示。5. 解：Form3窗体的界面如图A.19所示，有两个标签（Label1和Label2）、两个文本框（Text

19、Box1和TextBox2）和一个命令按钮Button。在该窗体上设计如下代码：Public Class Form3 Private Sub Button1_Click(ByVal sender As System.Object, _ ByVal e As System.EventArgs) Handles Button1.Click Dim i, n, sum As Integer n = Val(TextBox1.Text) sum = 0 For i = 1 To 10 sum = sum + fac(i) 调用函数过程后,进行累加 Next TextBox2.Text = Format

20、(sum) End Sub Function fac(ByVal n As Integer) As Integer Dim j As Integer Dim total As Integer = 1 For j = 1 To n total = total * j Next fac = total End Function Private Sub Form3_Load(ByVal sender As System.Object, _图A.20 Form3运行界面 ByVal e As System.EventArgs) Handles MyBase.Load TextBox1.Text = T

21、extBox2.Text = End SubEnd Class运行本窗体，输入n为5，单击“求值”命令按钮，结果如图A.20所示。练 习 题 6图A.21 Form1设计界面1. 答：略。2. 解：Form1窗体的界面如图A.21所示，只有一个标签Label1。在该窗体上设计如下代码：Public Class Form1 Private Sub Form1_Load(ByVal sender As System.Object, _ ByVal e As System.EventArgs) Handles MyBase.Load Me.BackgroundImage = _ System.Dra

22、wing.Image.FromFile(H:vb程序spring.jpg) End SubEnd Class图A.22 Form1运行界面图A.23 Form2设计界面运行本窗体，其结果如图A.22所示。3. 解：Form2窗体的界面如图A.23所示，有3个标签（Label1Label3）、两个文本框（TextBox1和TextBox2，TextBox2的Passwordchar属性设置为“*”）和一个命令按钮Button1。在该窗体上设计如下代码：Public Class Form2 Private Sub Button1_Click(ByVal sender As System.Objec

23、t, _ ByVal e As System.EventArgs) Handles Button1.Click If TextBox1.Text = 1234 Then If TextBox2.Text = 1234 Then MsgBox(用户名/口令正确，进入系统运行, vbOKOnly, 信息提示) 调用其他系统窗体 Else MsgBox(口令不正确,重新输入, vbOKOnly, 信息提示) TextBox2.Text = TextBox2.Focus() End If Else MsgBox(用户名口令不正确，重新输入, vbOKOnly, 信息提示)图A.24 Form2运行界面图A.25 Form3设计界面 TextBox1.Text = TextBox2.Text =