Get text from another application

c# sendmessage
sventevit picture sventevit · Dec 9, 2009 · Viewed 25.2k times · Source

I'd like to retrieve text from textbox in my another application. ProcessName from second application is 'TestTextBox', TextBox's name is 'textBox1'.

My code, which returns empty string:

[DllImport("user32.dll")]
static extern IntPtr SendMessage(IntPtr hWnd, uint Msg, long wParam, [MarshalAs(UnmanagedType.LPStr)] StringBuilder lParam);

Process[] processes = Process.GetProcessesByName("TestTextBox");
foreach (Process p in processes)
{
    IntPtr pFoundWindow = p.MainWindowHandle;
    const int WM_GETTEXT = 0x0D;
    StringBuilder sb = new StringBuilder();
    IntPtr retVal = SendMessage(pFoundWindow, WM_GETTEXT, 100, sb);
    MessageBox.Show(sb.ToString());
}

Answer

Dour High Arch picture Dour High Arch · Dec 9, 2009

What is the "another application"? Is it something you are writing? Could it be running on another machine? In another domain? Under another user account? Could the target application, form, or textbox ever change? Do you need asynchronous (i.e. non-blocking) communication between applications?

If the answer to any of those questions is "yes", you should consider using .Net Remoting. This is available from .Net 2.0.

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