🚀 go-pugleaf

"Robert L. Smith" <x@x> wrote in message
news:42a603ef$1@newsgroups.borland.com...

>     // this works
>     char buf[] = "my dog has fleas\n";
>     WriteFile(hPipeWrite, buf, sizeof(buf), &nWritten, NULL);

Of course it does, because you are writing to the pipe directly, not to
STDOUT.

>     // this doesn't work!
>     printf("I am feeling so sad\n");

Nor should it.  SetStdHandle() has no effect on the handles that the C
functions use.  The C library grabs the STDIN, STDOUT, and STDERR handles
once at program startup, stores them into an array, and uses the array for
all reading/writing operations.  SetStdHandle() does not touch those array
items at all.  The only offical way to redirect STDIN, STDOUT, and STDERR
from the C library perspective is to use freopen(), however it redirects to
files, not user-defined handles such as pipes.  As far as I know, the only
way to specify your own handle is to use _open_osfhandle() and then reassign
STDOUT directly, for example (untested):

    #include <io.h>
    #include <stdio.h>

    HANDLE hWritePipe = ...;
    int iPipe = _open_osfhandle(reinterpret_cast<long>(hWritePipe),
_O_TEXT);
    if( iPipe != -1 )
    {
        FILE *pFile = _fdopen(iPipe, "w");
        if( pFile )
        {
            *stdout = *pFile;
            // write to stdout as needed...
        }
    }

Once you have stdout redirected, you can optionally call setvbuf() if you
want to turn off the C library's native buffering, which will effectively
dump any written data to your pipe immediately on every C library writing
operation.

Also, if you want std::cout to be redirected as well, call the
ios::sync_with_stdio() function after redirectly STDOUT.


Gambit