Re: stdout redirection

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From: William DePalo [MVP VC++] (willd.no.spam_at_mvps.org)
Date: 10/23/04

  • Next message: William F. Kinsley: "Re: MC++ Unmanaged MFC calling Managed WinForm class" 
    Date: Sat, 23 Oct 2004 12:00:16 -0400

    "Nadav" <Nadav@discussions.microsoft.com> wrote in message
    news:37582031-D696-4C6F-94C8-05A2C047F7A3@microsoft.com...
    > I am trying to redirect stdout to a RichEdit control, this is done by
    > ...
    > fd = _open_osfhandle((long)GetStdHandle(STD_OUTPUT_HANDLE),_O_APPEND);
    > fp = _fdopen(fd,"w");
    > *stdout = *fp;
    > setvbuf(stdout, NULL, _IONBF, 0);
    > But apparently it doesn't work: '_open_osfhandle' returns -1.

    I resort to this redirection technique when I need to add more debug trace
    capability than is convenient with OutputDebugString().

    _If_ I recall correctly, when you redirect the standard output device of a
    console application, any output you do in the main module _or_ in a DLL gets
    redirected properly.

    However, if you AllocConsole() in a windowed application and redirect
    standard output to it, then the redirection works _only_ in the main module.
    Any DLL loaded by the executable still "thinks" that it does not have a
    standard output device because the executable image was not marked as a
    console application when the DLL's runtime was initialized.

    So, my _guess_ is that you need to pass the device handle of the console to
    whatever executable component is redirecting output and redirect its
    standard output as well. Of course, I might be wrong.

    Regards,
    Will

  • Next message: William F. Kinsley: "Re: MC++ Unmanaged MFC calling Managed WinForm class"

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