vb教程编程实例详解pdf_vb程序设计教程答案第四版

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实验8-7

在教学篇例8.7的基础上增加“修改确定”按钮以及用于定位记录的按钮面板，如图2.8.5所示，并编写时间过程。

解题，代码如下：

先建立标准模块，代码是：

Type studtype
    iNo As Integer
    strName As String * 20
    strSex As String * 1
    sMark As Single
End Type

再在窗体上建立相应的按钮等控件，窗体代码如下：

Dim Student As studtype
Dim Record_No As Integer
Sub Form_Load()
    Open “C:\STUDENT.DAT” For Random As #1 Len = Len(Student)
    Label1.Caption = LOF(1) / Len(Student)
    Close #1
    
    If Label1.Caption <> “0” Then Command3_Click ‘记录不为零，就显示第一条记录
End Sub

Sub Command1_Click() ‘追加记录
    With Student
        .iNo = Val(Text1.Text)
        .strName = Text2.Text
        .strSex = IIf(Option1.Value, “1”, “0”)
        .sMark = Val(Text3.Text)
    End With

    Open “C:\STUDENT.DAT” For Random As #1 Len = Len(Student)
    Record_No = LOF(1) / Len(Student) + 1
    Label1.Caption = Record_No
    Text4.Text = Record_No ‘加这句，当场修改记录就不用手工输入了
    Put #1, Record_No, Student
    Close #1
End Sub

Sub Command2_Click() ‘显示记录
    Open “C:\STUDENT.DAT” For Random As #1 Len = Len(Student)
    Record_No = Val(Text4.Text)
    Get #1, Record_No, Student
    Text1.Text = Student.iNo
    Text2.Text = Student.strName
    If Student.strSex = “1” Then
        Option1.Value = True
    Else
        Option2.Value = True
    End If
    Text3.Text = Student.sMark
    Record_No = LOF(1) / Len(Student)
    Close #1
End Sub

Private Sub Command3_Click() ‘第一条记录
    Open “C:\STUDENT.DAT” For Random As #1 Len = Len(Student)
    Record_No = 1
    Get #1, Record_No, Student
    Text1.Text = Student.iNo
    Text2.Text = Student.strName
    If Student.strSex = “1” Then
        Option1.Value = True
    Else
        Option2.Value = True
    End If
   
    Text3.Text = Student.sMark
    Text4.Text = “1”
    Close #1

End Sub
Private Sub Command4_Click() ‘下一条记录
    If Record_No = Val(Label1.Caption) Then
        MsgBox “已经是最后一条记录了”
        Exit Sub   ‘已经是最后一条记录就退出。
    End If

    Open “C:\STUDENT.DAT” For Random As #1 Len = Len(Student)
    Record_No = Record_No + 1
    Get #1, Record_No, Student
    Text1.Text = Student.iNo
    Text2.Text = Student.strName
    If Student.strSex = “1” Then
        Option1.Value = True
    Else
        Option2.Value = True
    End If
    Text3.Text = Student.sMark
    Text4.Text = Record_No
    Close #1
End Sub

Private Sub Command5_Click() ‘前一条记录
    If Record_No = 1 Then
        MsgBox “已经是第一条记录了”
        Exit Sub ‘已经是第一条记录就退出。
    End If

    Open “C:\STUDENT.DAT” For Random As #1 Len = Len(Student)
    Record_No = Record_No – 1
    Get #1, Record_No, Student
    Text1.Text = Student.iNo
    Text2.Text = Student.strName
    If Student.strSex = “1” Then
        Option1.Value = True
    Else
        Option2.Value = True
    End If
    Text3.Text = Student.sMark
    Text4.Text = Record_No
    Close #1
End Sub

Private Sub Command6_Click() ‘最后一条记录
    Open “C:\STUDENT.DAT” For Random As #1 Len = Len(Student)
    Record_No = Val(Label1.Caption)
    Get #1, Record_No, Student
    Text1.Text = Student.iNo
    Text2.Text = Student.strName
    If Student.strSex = “1” Then
        Option1.Value = True
    Else
        Option2.Value = True
    End If
    Text3.Text = Student.sMark
    Text4.Text = Label1.Caption
    Close #1
End Sub

Sub Command7_Click() ‘修改记录
    With Student
        .iNo = Val(Text1.Text)
        .strName = Text2.Text
        .strSex = IIf(Option1.Value, “1”, “0”)
        .sMark = Val(Text3.Text)
    End With

    Open “C:\STUDENT.DAT” For Random As #1 Len = Len(Student)
    Record_No = Val(Text4.Text)
    Put #1, Record_No, Student
    Close #1
End Sub