C# Signature:

[DllImport("kernel32.dll", SetLastError = true)]
static extern bool ReadProcessMemory(
    IntPtr hProcess,
    IntPtr lpBaseAddress,
    [Out] byte[] lpBuffer,
    int dwSize,
    out IntPtr lpNumberOfBytesRead);

[DllImport("kernel32.dll", SetLastError = true)]
static extern bool ReadProcessMemory(
    IntPtr hProcess,
    IntPtr lpBaseAddress,
    [Out, MarshalAs(UnmanagedType.AsAny)] object lpBuffer,
    int dwSize,
    out IntPtr lpNumberOfBytesRead);

[DllImport("kernel32.dll", SetLastError = true)]
static extern bool ReadProcessMemory(
    IntPtr hProcess,
    IntPtr lpBaseAddress,
    IntPtr lpBuffer,
    int dwSize,
    out IntPtr lpNumberOfBytesRead);

VB.Net Signature:

<DllImport("kernel32.dll", SetLastError:=true)> _
Public Shared Function ReadProcessMemory( _
    ByVal hProcess As IntPtr, _
    ByVal lpBaseAddress As IntPtr, _
    <Out()> ByVal lpBuffer As Byte(), _
    ByVal dwSize as Integer, _
    ByRef lpNumberOfBytesRead as Integer) As Boolean
End Function

<DllImport("kernel32.dll", SetLastError:=true)> _
Public Shared Function ReadProcessMemory( _
    ByVal hProcess As IntPtr, _
    ByVal lpBaseAddress As IntPtr, _
    <Out(),MarshalAs(UnmanagedType.AsAny)> ByVal lpBuffer As object, _
    ByVal dwSize as Integer, _
    ByRef lpNumberOfBytesRead as Integer) As Boolean
End Function

<DllImport("kernel32.dll", SetLastError:=True)> _
Public Shared Function ReadProcessMemory( _
    ByVal hProcess As IntPtr, _
    ByVal lpBaseAddress As IntPtr, _
    ByVal lpBuffer As IntPtr, _
    ByVal iSize As Integer, _
    ByRef lpNumberOfBytesRead As Integer) As Boolean
End Function

Notes:

None.

Tips & Tricks:

Using VB.NET you may need to substitute ByVal for ByRef when declaring: "lpBuffer" and "lpNumberOfBytesRead" for the method to work.

To read primitive values without boxing pass in a byte array to read the content. Use methods in the BitConverter class to convert the data.

On 64-bit systems lpNumberOfBytesRead returned as the 64-bit value.

You can also make aliases of the signatures above to pass the variable receiving the data by reference. e.g

<DllImport("kernel32.dll", SetLastError=true, EntryPoint="ReadProcessMemory")> _
Public Shared Function ReadVMInteger(
    ByVal hProcess As IntPtr,
    ByVal lpBaseAddress As IntPtr,
    ByRef lpBuffer As Integer,
    ByVal dwSize as Integer,
    ByRef lpNumberOfBytesRead as Integer) As Boolean
End Function

Sample Code:

Assuming you're trying to readout an integer which is four bytes long:

As you can see I prove a handle, and an adress.

I then create a new buffer the size of the adress.

(Note that this example is an integer you could also do it with strings but then return encoding.default.ascii etc.. )

public int ReadInt32(IntPtr hProcess, uint dwAddress)
{
    byte[] buffer = new byte[4];
    int bytesread;

    Win32Api.ReadProcessMemory(hProcess, dwAddress, buffer, 4, out bytesread);
    return BitConverter.ToInt32(buffer, 0);
}

Generic RPM was missing here. (Also added WPM -> WriteProcessMemory example)

public T Rpm<T>(IntPtr lpBaseAddress) where T : struct
{
    T[] buffer = new T[SizeOf<T>()];
    ReadProcessMemory(_gameProcess.Process.Handle, lpBaseAddress, buffer, SizeOf<T>(), out var bytesread);
    return buffer.First(); // [0] would be faster, but First() is safer. Eq of buffer[0] ?? default(T)
}

public T Rpm<T>(IntPtr lpBaseAddress, List<int> offsets) where T : struct
{
    IntPtr address = lpBaseAddress;

    var lastOffset = offsets.Last();
    offsets.RemoveAt(offsets.Count-1);

    foreach (var offset in offsets)
    {
       address = Rpm<IntPtr>(IntPtr.Add(address, offset));
    }

    return Rpm<T>(IntPtr.Add(address, lastOffset));
}

Alternative Managed API:

Do you know one? Please contribute it!

Please edit this page!

Do you have...

• helpful tips or sample code to share for using this API in managed code?
• corrections to the existing content?
• variations of the signature you want to share?
• additional languages you want to include?

Select "Edit This Page" on the right hand toolbar and edit it! Or add new pages containing supporting types needed for this API (structures, delegates, and more).