g++ newbie prblem - gcc-3.0.3 vs gcc-2.95.3

g++ newbie prblem - gcc-3.0.3 vs gcc-2.95.3

[Hillel (Sabba) Markowitz]

The following program builds and runs fine under 2.95.3 but does not compile 
under gcc-3.0.3  As a g++ newbie I must be doing something very obvious wrong.

Please respond via e-mail as I do not usually have access to the mailing list 
archive.

#include <stdio.h>
#include <stdlib.h>
#include <iostream.h>
#include <fstream.h>
#include <unistd.h>
main()
  {
    ofstream *fout = new ofstream (dup(1));
    *fout << "Hello World\n";
  }


When compiling with gcc-3.0.3 I get

r.cc: In function 'int main()':
r.cc:9 no matching function for call to 'std::basic_ofstream<char,
   std::char_traits<char> >::basic_ofstream(int)'
/usr/local/GCC-3.0/include/g++-v3/bits/std_iosfwd.h:84: candidates are:
   std::basic_ofstream<char, std::char_traits<char> >::basic_ofstream(const
   std::basic_ofstream<char, std::char_traits<char> >&)
/usr/local/GCC-3.0/include/g++-v3/bits/std_fstream.h:319:
   std::basic_ofstream<_CharT, _Traits>::basic_ofstream(const char*,
   std::_Ios_Openmode = (std::ios_base::out | std::ios_base::trunc)) [with
   _CharT = char, _Traits = std::char_trats<char>]
/usr/local/GCC-3.0/include/g++-v3/bits/std_fstream.h:313:
   std::basic_ofstream<_CharT, _Traits>::basic_ofstream() [with _CharT = char,
   _Traits = std::char_traits<char>]

-- 
Said the fox to the fish, "Join me ashore".
 The fish are the Jews, Torah is our water

Hillel (Sabba) Markowitz - sabbahem@bcpl.net

Re: g++ newbie prblem - gcc-3.0.3 vs gcc-2.95.3

[Claudio Bley]

>>>>> "Hillel" == Hillel (Sabba) Markowitz <sabbahem@bcpl.net> writes:

    Hillel> The following program builds and runs fine under 2.95.3
    Hillel> but does not compile under gcc-3.0.3 As a g++ newbie I
    Hillel> must be doing something very obvious wrong.

    Hillel> Please respond via e-mail as I do not usually have access
    Hillel> to the mailing list archive.

    Hillel> #include <stdio.h> #include <stdlib.h> #include
    Hillel> <iostream.h> #include <fstream.h> #include <unistd.h>
    Hillel> main() { ofstream *fout = new ofstream (dup(1)); *fout <<
    Hillel> "Hello World\n"; }

[snip]

The C++ Standard does *not* specify a facility to assign a file
descriptor to a file stream because file descriptors are OS dependent.

If you want to redirect standard I/O channels you should assign the
stream buffers of stream objects to each other:

ostream ostr(0);
ostr.rdbuf (cout.rdbuf ());


Claudio

Re: g++ newbie prblem - gcc-3.0.3 vs gcc-2.95.3

[Hillel (Sabba) Markowitz]

Claudio Bley wrote:
> 
> >>>>> "Hillel" == Hillel (Sabba) Markowitz <sabbahem@bcpl.net> writes:
> 
>     Hillel> The following program builds and runs fine under 2.95.3
>     Hillel> but does not compile under gcc-3.0.3 As a g++ newbie I
>     Hillel> must be doing something very obvious wrong.
> 
>     Hillel> Please respond via e-mail as I do not usually have access
>     Hillel> to the mailing list archive.
> 
>     Hillel> #include <stdio.h> #include <stdlib.h> #include
>     Hillel> <iostream.h> #include <fstream.h> #include <unistd.h>
>     Hillel> main() { ofstream *fout = new ofstream (dup(1)); *fout <<
>     Hillel> "Hello World\n"; }
> 
> [snip]
> 
> The C++ Standard does *not* specify a facility to assign a file
> descriptor to a file stream because file descriptors are OS dependent.
> 
> If you want to redirect standard I/O channels you should assign the
> stream buffers of stream objects to each other:
> 
> ostream ostr(0);
> ostr.rdbuf (cout.rdbuf ());
> 
> Claudio


Thank you for your response.  I tried your suggestion and it does work. 
However, we need to be able to outprint the results of fprintf to stderr
(legacy code already written).  If the user specifies on the command
line that he wants to use a log file instead of stderr, then we want to
close the stderr and open the log file.  In the command line parser we
have

close(2);
fopen(logFile, "w"):

From that point on, all fprintf(stderr, "..."); calls will be written to
the log file (or the screen if the command line switch did not trigger
the close and reopen.

g++-2.95.3 implemented this correctly, but g++3.0.3 do not.  Is there a
recommended way to code this.

I would prefer not to have to change all the fprintf legacy code if I
can avoid it.  It would be preferable if the code change also handled
cerr<< ...; as well as this is a mixed c, c++ set of routines and has
both legacy and new code.   However, the main question is with the
fprintf.

As before, please respond to sabbahem@bcpl.net or
Sabba.Hillel@verizon.net as I do not have reliable access to the mailing
list.

-- 
Said the fox to the fish, "Join me ashore".
The fish are the Jews, Torah is our water.

Hillel (Sabba) Markowitz
sabbahem@bcpl.net, Sabba.Hillel@verizon.net