using a UDT in multiple applications

[MerrionComputin]

For the sake of simplicity this call can be wrapped up in two utility functions - one of which returns a Long value from a pointer in another process' memory and another wich returns a string from a pointer in another application's memory thus:-

Private Declare Function ReadProcessMemoryBytes Lib "kernel32" Alias "ReadProcessMemory" (ByVal hProcess As Long, ByVal lpBaseAddress As Long, lpBuffer As Byte, ByVal nSize As Long, lpNumberOfBytesWritten As Long) As Long
 
Public Function LongFromOutOfprocessPointer(ByVal hProcess As Long, ByVal lpAddress As Long) As Long
 
Dim lRet As Long
Dim lBytesWritten As Long
 
Call ReadProcessMemory(hProcess, lpAddress, ByVal VarPtr(lRet), Len(lRet), lBytesWritten)
If lBytesWritten > 0 Then
    LongFromOutOfprocessPointer = lRet
End If
 
End Function
 
Public Function StringFromOutOfProcessPointer(ByVal hProcess As Long, ByVal lpString As Long, ByVal Length As Long, ByVal Unicode As Boolean) As String
 
Dim buf() As Byte
Dim lRet As Long
Dim lBytesWritten As Long
Dim sTemp As String
 
ReDim buf(Length) As Byte
 
lRet = ReadProcessMemoryBytes(hProcess, lpString, buf(0), Length, lBytesWritten)
If lBytesWritten = 0 And Err.LastDllError = 0 Then
    While lBytesWritten = 0 And Length > 0
        Length = Length - 1
        lRet = ReadProcessMemoryBytes(hProcess, lpString, buf(0), Length, lBytesWritten)
    Wend
Else
    If Err.LastDllError Then
        Debug.Print LastSystemError
    End If
End If
If lRet <> 0 Then
    If Unicode Then
        StringFromOutOfProcessPointer = StrConv(buf, vbFromUnicode)
    Else
        For lRet = 0 To lBytesWritten
            If buf(lRet) = 0 Then
                Exit For
            End If
            sTemp = sTemp & Chr$(buf(lRet))
        Next lRet
        StringFromOutOfProcessPointer = sTemp
    End If
Else
    If Err.LastDllError Then
        Debug.Print LastSystemError
    End If
End If

In the second one I have added som error trapping which I recommend using after any API call. The code for LastSystemError is:

Private Declare Function FormatMessage Lib "kernel32"  _ 
              Alias "FormatMessageA" (ByVal dwFlags As Long,  _ 
                        ByVal lpSource As Long, _ 
                        ByVal dwMessageId As Long, _ 
                        ByVal dwLanguageId As Long, _ 
                        ByVal lpBuffer As String,  _ 
                        ByVal nSize As Long, _ 
                       Arguments As Long) As Long
 
'\\ -- [ LastSystemError ]----------------------------------
'\\ Returns the message from the system which describes the
'\\ last dll error to occur, as
'\\ held in Err.LastDllError. This function should be
'\\ called as soon after the API call
'\\ which might have errored, as this member can be reset
'\\ to zero by subsequent API calls.
'\\ --------------------------------------------------------
Public Function LastSystemError() As String
 
Const FORMAT_MESSAGE_FROM_SYSTEM = &H1000
Dim sError As String * 500 '\\ Preinitilise a string buffer to put any error message into
Dim lErrNum As Long
Dim lErrMsg As Long
 
lErrNum = Err.LastDllError
 
lErrMsg = FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM, 0, lErrNum, 0, sError, Len(sError), 0)
 
LastSystemError = Trim(sError)
 
End Function