Question

I have

Private Declare Function ReadProcessMemory Lib "kernel32" Alias "ReadProcessMemory" (ByVal hProcess As Integer, ByVal lpBaseAddress As Integer, ByRef lpBuffer As Integer, ByVal nSize As Integer, ByRef lpNumberOfBytesWritten As Integer) As Integer

But I also need

Private Declare Function ReadProcessMemory Lib "kernel32" Alias "ReadProcessMemory" (ByVal hProcess As Integer, ByVal lpBaseAddress As Integer, ByRef lpBuffer As Single, ByVal nSize As Integer, ByRef lpNumberOfBytesWritten As Integer) As Integer

And some other variations. So, as in the example above, lpBuffer as Single instead of Integer. How can I achieve this?

UPDATE: Alrighty, now I’m doing this:

Imports System.Math
Imports System.Threading
Imports System.Runtime.InteropServices

Public Class Form1

'Declare ReadProcessMemory with lpBuffer As IntPtr
Private Declare Function ReadProcessMemory Lib "kernel32" Alias "ReadProcessMemory" (ByVal hProcess As Integer, ByVal lpBaseAddress As Integer, ByRef lpBuffer As IntPtr, ByVal nSize As Integer, ByRef lpNumberOfBytesWritten As Integer) As Integer

'This is the function I am now having trouble with
Public Function memfloat(ByVal address As Long, ByVal processHandle As IntPtr)
        Dim floatvalueinmemory As Single
        ReadProcessMemory(processHandle, address, floatvalueinmemory, 4, 0)
        Dim letstryagain As Single 'floatvalueinmemory didn't give the desired result, so going to try to TryParse
        Single.TryParse(floatvalueinmemory, letstryagain)
        Return CStr(letstryagain) 'returns the same result as floatvalueinmemory did
    End Function

End Class

Partial Public Class NativeMethods
    <DllImport("user32.dll")> _
    Public Shared Function ReadProcessMemory(ByVal hProcess As System.IntPtr, ByVal lpBaseAddress As IntPtr, ByVal lpBuffer As System.IntPtr, ByVal nSize As UInteger, ByVal lpNumberOfBytesRead As IntPtr) As Boolean
    End Function
End Class

The memfloat function used to return something like “-75,48196”, now it returns something like “-1,012555E+09” (the actual values don’t match, just using these as an example), this is why I wanted to declare multiple times in the first place.. how do I convert from the IntPtr to a Single ?

What does work is:

Public Function memstring(ByVal address As Long, ByVal length As Int32, ByVal processHandle As IntPtr)
    Dim stringinmemory As Long
    Dim ret1 As Byte() = Nothing
    Dim tStr(length) As Char
    Dim retStr As String = ""
    For i As Int32 = 0 To length - 1
        ReadProcessMemory(processHandle, address + i, stringinmemory, 1, 0)
        ret1 = BitConverter.GetBytes(stringinmemory)
        tStr(i) = System.Text.Encoding.ASCII.GetString(ret1) : retStr += tStr(i)
    Next
    Return retStr
End Function

This correctly returns the memory value as string. So yeah, now it’s just the Single that’s causing issues.

Answer 1

You are using the Alias keyword anyway, so take advantage of it:

Private Declare Function ReadProcessMemoryInt Lib "kernel32" _
    Alias "ReadProcessMemory" (ByVal hProcess As Integer, _
                               ByVal lpBaseAddress As Integer, _
                               ByRef lpBuffer As Integer, _
                               ByVal nSize As Integer, _
                               ByRef lpNumberOfBytesWritten As Integer) As Integer

Private Declare Function ReadProcessMemorySingle Lib "kernel32" _
    Alias "ReadProcessMemory" (ByVal hProcess As Integer, _
                               ByVal lpBaseAddress As Integer, _
                               ByRef lpBuffer As Single, _
                               ByVal nSize As Integer, _
                               ByRef lpNumberOfBytesWritten As Integer) As Integer

The name you give to the function can be arbitrary. Only the Alias name must match the name in the library. In your code, you can refer to ReadProcessMemoryInt and ReadProcessMemorySingle (or whatever name you chose).

(Note: I didn’t check whether you are actually using the API correctly, I’ve just answered your question about how to define the same API function twice with different signatures.)