Como utilizar o acesso a ficheiros binários com o Visual Basic

Passos para criar este exemplo:

1. Inicie um novo projecto EXE padrão do Visual Basic. É criado o Form1 por predefinição.
2. No menu Project , seleccione Add Module para adicionar um módulo padrão ao projecto. Módulo1 é criado por predefinição.
3. No menu Project , seleccione Propriedades do projeto1 para apresentar a caixa de diálogo Propriedades do projecto . Seleccione o separador ' Geral ' e altere o objecto de arranque para Sub Main .
4. Adicione o seguinte código à secção General Declarations do Module1:

   Option Explicit
   ' define structure of a variable-length record
   Type Person_VariableLength
       ID               As Integer
       MonthlySalary    As Currency
       LastReviewDate   As Long
       FirstName        As String
       LastName         As String
       Title            As String
       ReviewComments   As String
   End Type
   
   ' define structure of a fixed-length record
   Type Person_FixedLength
       ID               As Integer
       MonthlySalary    As Currency
       LastReviewDate   As Long
       FirstName        As String * 15
       LastName         As String * 15
       Title            As String * 15
       ReviewComments   As String * 150
   End Type
   
   ' variables for sample data
   Private binSampleOne As Person_VariableLength
   Private binSampleTwo As Person_VariableLength
   Private randomSampleOne As Person_FixedLength
   Private randomSampleTwo As Person_FixedLength
   
   ' record number for use with random (fixed-length) file
   Private intRecNum As Integer
   
   Public Sub main()
       buildSampleRecords
       demonstrateBinary
       demonstrateRandom
   End Sub
   
   Private Function demonstrateBinary()
       ' open the file and write the records
       Open "c:\BINsample" For Binary As #1
       Put #1, , binSampleOne
       Put #1, , binSampleTwo
       Close #1
       
       ' open the file and read the records
       Open "c:\binSample" For Binary As #1
       Dim udtPerson As Person_VariableLength
       Do While Not EOF(1)
           Get #1, , udtPerson
           ' display selected values
           With udtPerson
               Debug.Print .FirstName
               Debug.Print .LastName
               Debug.Print .ReviewComments
           End With
       Loop
       Close #1
   End Function
   
   Private Function demonstrateRandom()
       ' open the file and write the records
       Dim recSize As Person_FixedLength
       Open "c:\Randomsample" For Random As #1 Len = Len(recSize)
       Put #1, 1, randomSampleOne
       Put #1, 2, randomSampleTwo
       Close #1
       
       'open the file and read the records
       Dim udtPerson As Person_FixedLength
       Open "c:\randomsample" For Random As #1 Len = Len(udtPerson)
       ' demonstrate random access capability by reading file backwards
       For intRecNum = 2 To 1 Step -1
           Get #1, intRecNum, udtPerson
           ' display selected values
           With udtPerson
               Debug.Print .FirstName
               Debug.Print .LastName
               Debug.Print .ReviewComments
           End With
       Next intRecNum
       Close #1
   End Function
   
   Private Sub buildSampleRecords()
   ' routine to build sample records
   ' note that populating the data of the User Defined Type is the
   ' same regardless of fixed or variable length members
      With binSampleOne
           .ID = 1
           .MonthlySalary = 50000
           .LastReviewDate = #2/2/2000#
           .FirstName = "Wilma"
           .LastName = "Flintstone"
           .Title = "Movie Star"
           .ReviewComments = "Contract renewed for sequel"
       End With
       With binSampleTwo
           .ID = 2
           .MonthlySalary = 50000
           .LastReviewDate = #2/2/2000#
           .FirstName = "Fred"
           .LastName = "Flintstone"
           .Title = "Movie Star"
           .ReviewComments = "Replace with Clint Eastwood for sequel"
       End With
       With randomSampleOne
           .ID = 1
           .MonthlySalary = 50000
           .LastReviewDate = #2/2/2000#
           .FirstName = "Wilma"
           .LastName = "Flintstone"
           .Title = "Movie Star"
           .ReviewComments = "Contract renewed for sequel"
       End With
       With randomSampleTwo
           .ID = 2
           .MonthlySalary = 50000
           .LastReviewDate = #2/2/2000#
           .FirstName = "Fred"
           .LastName = "Flintstone"
           .Title = "Movie Star"
           .ReviewComments = "Replace with Clint Eastwood for sequel"
       End With
   End Sub
   					

5. Certifique-se de que a janela Immediate é apresentada. Se não estiver, terá de seleccioná-lo no menu Ver .
6. Execute o projecto e note que os resultados são apresentados na janela Immediate.

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