Calling SendMessage (P/Invoke) keeps crashing

Question

I am having to write an application that communicates with a third-party program (AOL, I\'m sorry. :()

Doing a lot of research I found some ways to do this with P/In

Answer 1

Did you manage to solve the "Attempted to read or write protected memory." error? t0mm13b's answer seems to allocate a StringBuilder whose buffer is one character too small (to accommodate the trailing '\0').

Here's code that works for me:

[DllImport("user32.dll", EntryPoint = "SendMessage", SetLastError = true)]
private static extern Int32 SendMessageByString(IntPtr wnd, UInt32 msg, Int32 WParam, StringBuilder output);
const int WM_GETTEXTLENGTH = 0x000e;
const int WM_GETTEXT = 0x000d;

public static string GetText(IntPtr hWnd)
{
    int len = SendMessageByString(hWnd, WM_GETTEXTLENGTH, 0, null);
    var sb = new StringBuilder(len + 1);  // +1 is for the trailing '\0'
    SendMessageByString(hWnd, WM_GETTEXT, sb.Capacity, sb);
    return sb.ToString();
}