This vb program is a simple form with a button and a text box, start two instances of it, and you’ll see that the textbox updates in the second window when the button in the first window is clicked.


Public Class Form1

Private Structure MMFContents

_
Public Value As Integer

_
Public Large As Byte

Public Sub Init()
Value = 101
End Sub

Public Sub Increment()
Value += 1
End Sub

End Structure

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

Dim m As System.IO.MemoryMappedFiles.MemoryMappedFile = GetMMF()

Dim a As System.IO.MemoryMappedFiles.MemoryMappedViewAccessor
a = m.CreateViewAccessor()

Dim c As New MMFContents
a.Read(0, c)

c.Increment()

a.Write(0, c)

TextBox1.Text = c.Value

Dim x As New System.Xml.Serialization.XmlSerializer(GetType(MMFContents))
‘x.Serialize()
End Sub

Private Function GetMMF() As System.IO.MemoryMappedFiles.MemoryMappedFile

Dim m As System.IO.MemoryMappedFiles.MemoryMappedFile

Try
m = System.IO.MemoryMappedFiles.MemoryMappedFile.OpenExisting(“fred2″)
Catch ex As System.IO.FileNotFoundException
m = System.IO.MemoryMappedFiles.MemoryMappedFile.CreateNew(“fred2″, System.Runtime.InteropServices.Marshal.SizeOf(GetType(MMFContents)))
Dim a As System.IO.MemoryMappedFiles.MemoryMappedViewAccessor
a = m.CreateViewAccessor()
Dim c As New MMFContents
c.Init()
a.Write(0, c)
End Try

Return m

End Function

Private Sub Timer1_Tick(ByVal sender As Object, ByVal e As System.EventArgs) Handles Timer1.Tick

Dim m As System.IO.MemoryMappedFiles.MemoryMappedFile = GetMMF()

Dim a As System.IO.MemoryMappedFiles.MemoryMappedViewAccessor
a = m.CreateViewAccessor()

Dim c As New MMFContents
a.Read(0, c)
TextBox1.Text = c.Value

End Sub

End Class

This is the simplest example which shows how to get Memory Mapped Files working. I'm now looking at how to serialize a dataset onto a MMF, and will post separately.

This article here gives the basis for an easy way of usig floats:

http://www.sitepoint.com/blogs/2005/02/26/simple-clearing-of-floats/

basically all you have to do is this (excuse the inline css – obviously this has to go in a css file):

<div id=”floatcontainer” style=”overflow:auto”>

 <div id=”floatcolumn1″ style=”float:left;width:700px”>content panel1</div>

 <div id=”floatcolumn2″ style=”float:left;width:200px”>content panel2</div>

</div>

now those inner divs can contain nested floats using this same html, and it all just works.

Note:

1. you have to specify width

2. the contents within the inner divs should not stretch the div horizontally (but most content will wrap no problem)

3. dont use the clear attribute at all

InitVariant(&varReturn);
if (AutoWrap(DISPATCH_METHOD, &varReturn, propset, fSysAllocString(WMITEXT(“Item”)), 1, param1))
{
prop = varReturn.pdispVal;

InitVariant(&varReturn);
if (AutoWrap(DISPATCH_PROPERTYGET, &varReturn, prop, fSysAllocString(WMITEXT(“Value”)), 0))
{
switch (varReturn.vt)
{
case 8204: // lVal Array
{
SAFEARRAY *psa = varReturn.parray;
long lStartIndex = 0;
long lEndIndex = 0;
SafeArrayGetLBound(psa, 1, &lStartIndex);
SafeArrayGetUBound(psa, 1, &lEndIndex);
SAFEARRAY* arrayAccess = NULL;
SafeArrayAccessData(psa, (void **) & arrayAccess);
long arrIndex[1];
*soutputbuffer4 = 0;

for (int i = lStartIndex; i lVal;
if (*soutputbuffer4 > 0) break;
}
SafeArrayDestroy(psa);
SafeArrayUnaccessData(psa);
}
break;

default:
*soutputbuffer4 = varReturn.intVal;
break;
}
}
if (prop) prop->Release();
}
}
}

I couldn’t be bothered to  analyse why one version works and the other version didn’t. Here’s a version that works in VB.NET 2005

Public Class Form1Private Declare Function inet_addr Lib “wsock32.dll” (ByVal s As String) As Integer

Private Declare Function SendARP Lib “iphlpapi.dll” (ByVal DestIP As Integer, ByVal SrcIP As Integer, ByRef pMACAddr As Integer, ByRef PhyAddrLen As Integer) As Integer

Private Declare Sub CopyMemory Lib “kernel32″ Alias “RtlMoveMemory” (ByRef dst As Byte, ByRef src As Integer, ByVal bcount As Integer)Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.ClickDim sIP As String

sIP = “192.168.1.4″

Dim inet As Integer

inet = inet_addr(sIP)

Dim pMACAddr As Integer

Dim i As Short

Dim sResult As String = “”

If SendARP(inet, 0, pMACAddr, 6) = 0 Then

CopyMemory(b(0), pMACAddr, 6)

For i = 0 To 5sResult = sResult & Right(“0″ & Hex(b(i)), 2)

If i < 5 Then sResult &= “-”Next

End If

MsgBox(sResult)

End SubEnd Class

Private Function AccountFromSID(ByVal sSid As String) As String

Dim sid As New System.Security.Principal.SecurityIdentifier(sSid)
Dim sFull As String = sid.Translate(GetType(System.Security.Principal.NTAccount)).ToString
Dim sSplit() As String = sFull.Split("\")
Return sSplit(sSplit.Length - 1)

End Function