Redirecting all stdout commands

[Morpheus]

I am trying to test a function that outputs text to the standard
output, presumably using a cout call. I do not have access to the
source, but need to test the output. Is this possible?

I can technically create an executable that calls the function and then
using a command prompt call the exexutable using the > output.txt
redirector but I would prefer to do everything within the application
itself. Is there a way for force an output to screen to a file or
string without having access to the cout call itself? ( would be easy
to do if I could simply do outfile << myText but the output is coming
from a function in a DLL for example).

example:

OutputMethod() // Inaccessible code that can not be modified
{
std::cout << "This is some text" << std::endl;
}

int main() // My Code
{
...
Redirect stdout to a text file
...
OutputMethod(); // Call the method and have it output to a file
instead of the screen
...
Verify the output file to see it's contents
...
}

Thanks,
Adam

[Victor Bazarov]

Morpheus wrote:

I am trying to test a function that outputs text to the standard
output, presumably using a cout call. I do not have access to the
source, but need to test the output. Is this possible?

I can technically create an executable that calls the function and
then using a command prompt call the exexutable using the > output.txt
redirector but I would prefer to do everything within the application
itself. Is there a way for force an output to screen to a file or
string without having access to the cout call itself? ( would be easy
to do if I could simply do outfile << myText but the output is coming
from a function in a DLL for example).

example:

OutputMethod() // Inaccessible code that can not be modified
{
std::cout << "This is some text" << std::endl;
}

int main() // My Code
{
...
Redirect stdout to a text file
...
OutputMethod(); // Call the method and have it output to a file
instead of the screen
...
Verify the output file to see it's contents
...
}

Isn't there something about this in the FAQ? If not, google for
"redirecting standard output". It's been done countless times.

V
--
Please remove capital 'A's when replying by e-mail
I do not respond to top-posted replies, please don't ask

[Morpheus]

I am sure it has been done, in fact I think I remember doing this back
some 10 years ago in C but redirecting to a printer. Have you actually
tried that search in Google? All you get are references to the >
operator in a command line environment. Unless you misunderstood the
question...

I will keep looking thought the FAQ unless someone else has it fresh in
their minds and can help.

[Rolf Magnus]

Morpheus wrote:

I will keep looking thought the FAQ unless someone else has it fresh in
their minds and can help.

You can replace cout's streambuf with an own one that writes the data where
you want it. If you don't want to limit it to cout, but also C stdout,
there is no standard C+++ way. On a POSIX system, you might want to have a
look at the dup2() function.

[Morpheus]

Thanks Rolf, the dup2 method seems to work perfectly for the cout
calls. If I want to do the same for C's printf, is there no way to
accomplish this?

The code: (albeit not pretty - found on the web )
-----------------------------------------
int old;
FILE *DataFile;

old = _dup( 1 ); /* "old" now refers to "stdout" */
DataFile = fopen( "C:\\data.txt", "w" );
/* stdout now refers to file "data" */
if( -1 == _dup2( _fileno( DataFile ), 1 ) )
{
perror( "Can't _dup2 stdout" );
exit( 1 );
}
std::cout << "Test";

/* Flush stdout stream buffer so it goes to correct file */
fflush( stdout );
fclose( DataFile );
_dup2( old, 1 );
-----------------------------------------

When doing this the cout is redirected to the text file I specified.
My only problem now is the older code. The classes under test all
derive from a base class that defines a method called dump() which
dumps thier contents to the screen. The older classes implementing
this method are using printf while the newer ones are using cout.
Knowing which does what I can tweak the tests to use the right redirect
for each class. Only problem is I have not been successful doing this
with a printf. Any suggestions?

[Alex Vinokur]

"Morpheus" <ad***********@gmail.com> wrote in message news:11********************@g10g2000cwb.googlegrou ps.com...

I am sure it has been done, in fact I think I remember doing this back
some 10 years ago in C but redirecting to a printer. Have you actually
tried that search in Google? All you get are references to the >
operator in a command line environment. Unless you misunderstood the
question...

I will keep looking thought the FAQ unless someone else has it fresh in
their minds and can help.

Look at

Redirecting cout/cerr <--> file : streambuf-method
http://groups.google.com/group/alt.s...4204134e9956a0

Redirecting cin <--> file
http://groups.google.com/group/alt.s...1d1032e2915ffd

Redirecting stdout <--> file
http://groups.google.com/group/alt.s...fdaef5e8fd79b5

Redirecting stdin <--> file
http://groups.google.com/group/alt.s...a6267142360edb
Also:
http://alexvn.freeservers.com/s1/download.html
* Redirecting cout/cerr <--> file
* Redirecting cin <--> file
* Redirecting stdout <--> file
* Redirecting stdin <--> file
--
Alex Vinokur
email: alex DOT vinokur AT gmail DOT com
http://mathforum.org/library/view/10978.html
http://sourceforge.net/users/alexvn

[Morpheus]

Shoot... I got really exited when I saw this but then noticed it was
Unix specific. I am running a Win32 system and the same calls do not
seem to work. Should I report this on a Win32 specific site?

[red floyd]

Morpheus wrote:

Shoot... I got really exited when I saw this but then noticed it was
Unix specific. I am running a Win32 system and the same calls do not
seem to work. Should I report this on a Win32 specific site?

Look up freopen()

[Alex Vinokur]

Morpheus wrote:

Shoot... I got really exited when I saw this but then noticed it was
Unix specific. I am running a Win32 system and the same calls do not
seem to work. Should I report this on a Win32 specific site?

Yes, it is UNIX-specific.
You have three options:
1) Find (write) similar _platform-independent_ program;
2) Use Cygwin on Win32 (I compiled my UNIX-specific program with Cygwin
GNU g++ on Win32);
3) Ask your question on microsoft.* newsgroups.

Regards,

--
Alex Vinokur
email: alex DOT vinokur AT gmail DOT com
http://mathforum.org/library/view/10978.html
http://sourceforge.net/users/alexvn