Save and Load Array Structure Easy

[BenJones]

Hi this is a very simple example of how you can save arrays of Structure to files you remember how easy this was in VB6 well it almost the same. This example just shows how to save data using a basic person example.

Ok start a new forms project add two commend buttons

Button1
Name : cmdSave
Text : Save

Button2
Name : cmdLoad
Text : Load

Next add the code, then hit the load button.
This will save a small data example button load will display persons name in message box. Hope you find it useful comments suggestions are welcome.

Code

Option Explicit On
 
Public Class Form1
 
    Private Structure TPerson
        Dim Id As Integer
        Dim Name As String
        Dim Age As Integer
    End Structure
 
    Private Persons() As TPerson
    Private PersonCount As Integer
 
    Private Sub Reset()
        'Reset person count and array
        PersonCount = 0
        Erase Persons
    End Sub
 
    Private Sub AddPerson(ByVal ID As Integer, ByVal Name As String, ByVal Age As Integer)
        ReDim Preserve Persons(PersonCount)
        'Add person to persons
        With Persons(PersonCount)
            .Id = ID
            .Name = Name
            .Age = Age
        End With
        'INC Counter
        PersonCount += 1
    End Sub
 
    Private Function LoadFromFile(ByVal Source As String) As Boolean
        Dim fp As Integer = FreeFile()
        Dim sig(2) As Char
 
        FileOpen(fp, Source, OpenMode.Binary, OpenAccess.Read)
        'Get header
        FileGet(fp, sig(0))
        FileGet(fp, sig(1))
        FileGet(fp, sig(2))
 
        If (New String(sig)) <> "BAG" Then
            Return False
        Else
            'Get person count
            FileGet(fp, PersonCount)
            'Get person records.
            ReDim Preserve Persons(PersonCount)
            FileGet(fp, Persons)
            FileClose(fp)
            'Return good value
            Return True
        End If
 
    End Function
 
    Private Sub WriteToFile(ByVal Source As String)
        Dim fp As Integer = FreeFile()
        Dim sig(2) As Char
 
        'Setup header
        sig(0) = "B"
        sig(1) = "A"
        sig(2) = "G"
 
        FileOpen(fp, Source, OpenMode.Binary, OpenAccess.Write)
        FilePut(fp, sig(0))
        FilePut(fp, sig(1))
        FilePut(fp, sig(2))
        FilePut(fp, Persons.Length - 1)
        FilePut(fp, Persons)
        FileClose(fp)
 
    End Sub
 
    Private Sub cmdSave_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdSave.Click
        'Add some random people.
        AddPerson(0, "Ben", 35)
        AddPerson(1, "Joe", 25)
        AddPerson(2, "Gemma", 32)
        AddPerson(3, "Bill", 56)
        AddPerson(4, "Jack", 24)
        'Write to filename.
        WriteToFile("C:\out\data\data.txt")
        'Reset
        Reset()
    End Sub
 
    Private Sub cmdLoad_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdLoad.Click
        'Load persons data.
        If LoadFromFile("C:\out\data\data.txt") <> True Then
            'Show message message.
            MessageBox.Show("Error loading data", "Error", MessageBoxButtons.OK,
                            MessageBoxIcon.Information)
        Else
            'Show persons
            For x As Integer = 0 To PersonCount
                MessageBox.Show(Persons(x).Name, "", MessageBoxButtons.OK,
                                MessageBoxIcon.Information)
            Next
            'Reset
            Reset()
        End If
    End Sub
End Class

[minitech]

You really, really, really shouldn't use the VB6-style FileXXX methods. Instead, use the classes in System.IO. Plenty of good resources out there.

[jimpie]

srry posted to wrong thread