我做了一个读取和写入文件的小东西 ，但是在写入文件的时候总是把原来的给覆盖了`
我知道在写顺序文件的时候是可以加在后面的
但是我用在二进制文件的时候就不行` 我想请教各位！
下面是我的代码：
Option Explicit

Private Type Student
StuID As Integer
SName As String
Marks As Integer
Grade As String
End Type

Private Sub Command1_Click()
Dim Emp1 As Student
Dim RecordNumber As Integer
RecordNumber = 1
If TxtID.Text = "" Or TxtName.Text = "" Or TxtMark.Text = "" Or TxtGrade.Text = "" Then
MsgBox "不能为空！", 64
End If

Dim fileNumber As Long
fileNumber = FreeFile
Open App.Path & "\File.txt" For Binary As #fileNumber

Emp1.StuID = TxtID.Text
Emp1.SName = TxtName.Text
Emp1.Marks = TxtMark.Text
Emp1.Grade = TxtGrade.Text

Put #fileNumber, , Emp1
Close #fileNumber

End Sub

Private Sub Command2_Click()

Dim Emp1 As Student
Dim RecordNumber As Integer
RecordNumber = 1

Dim fileNumber As Long
fileNumber = FreeFile
Open App.Path & "\File.txt" For Binary As #fileNumber

Get #fileNumber, , Emp1

Debug.Print Emp1.StuID
Debug.Print Emp1.SName
Debug.Print Emp1.Marks
Debug.Print Emp1.Grade
Close #fileNumber
End Sub

Private Sub Command3_Click()
End
End Sub