Get text from another application

I'd like to retrieve text from textbox in my another application. ProcessName from开发者_如何学运维 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());
}

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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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In june there was a discussion of how to find the handle of a child control, perhaps this helps.

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You are getting the WindowHandle of the main Form in the code you posted, according to MSDN a GETTEXT message to a Form should return its title. If you want to get text from a TextBox you should be passing the WindowHandle of the TextBox as the first argument.

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You could use Windows API like others have mentioned or you could use a library like AutoIt that might make the task a little easier. Not sure what your requirements are.