How to capture "printfs" from unmanaged C++

I posted this to the interop group. I'm reposting to troll for a few
more ideas.

In my managed C# app we capture trace statements and direct them to a
log file using trace listeners. Part of the app uses unmanaged C++
dlls, and unfortunately, the C++ printfs don't get picked up and are
simply printed to the console window.

Is there any way I can capture the output of the printfs and then
redirect them to the same file that the trace listener is writing to?

I do have access to the unmanaged C++ code if the solution involves
not using printfs. The important thing is that the C++ printfs and the
C# trace messages end up in the same file.

One solution from the interop group was to compile the C++ with /clr
and then replace the printfs with Trace.WriteLine(). Any less invasive
techniques. Maybe somehow redirecting the printfs to someplace that
can be picked up by .Net.

Thanks

Mitch

Peter
Wed Mar 12 18:32:39 CDT 2008

On Wed, 12 Mar 2008 13:33:41 -0700, <barker7@yahoo.com> wrote:

> [...]
> Is there any way I can capture the output of the printfs and then
> redirect them to the same file that the trace listener is writing to?
>
> I do have access to the unmanaged C++ code if the solution involves
> not using printfs. The important thing is that the C++ printfs and the
> C# trace messages end up in the same file.

It's been some time now, but my recollection is that the standard CRT has
a provision for overriding the default stdout stream. You could do that
in a single place in the C++ code, and then in that overridding output
redirect the output back up to the managed log file via the usual managed
mechanisms.

I apologize for not having the details as to how to redirect stdout from
within the process but this is, after all, a newsgroup for managed code.
:) I assume that if you posted the same question to a forum specifically
about using C++ and the standard CRT, they'd be able to tell you more
details. Or you might be able to find it in the C++ reference docs on
MSDN.

Pete