copying cout and vasprintf

copying cout and vasprintf

[Eddy Ilg]

Hi gcc gurus,

I want to output log information from my program to either cout or a file. I want it somewhat like this; 

ostream log_stream;

if (output_stout) {
  log_stream=cout;
} else if (output_file) {
  log_stream=ofstream(log_file);
}

By just trying log_stream=cout; I get this though:
/usr/include/g++/streambuf.h:128: `ios::ios(const ios &)' is private
log.cc:16: within this context

How can I do something like the above?

Another question: I want to use vasprintf(). This does not seem to be ANSI. I tried the following:
#define __USE_GNU
#include <stdio.h>
#include <stdlib.h>

void foo() 
{
  vasprintf(..)
}

g++ tells me that vasprintf is not defined. Do I have to use another preprocessor define that __USE_GNU?


Thanks a lot 


Eddy

Re: copying cout and vasprintf

[John Love-Jensen]

Hi Eddy,

Use:

ostream* log_stream;
bool log_stream_delete = false; // Ownership and management.

if(output_stout) {
  log_stream = &cout;
} else if(output_file) {
  log_stream_delete = true;
  log_stream = new ofstream(log_file);
}

*log_stream << "Hello world." << endl;  // Note the "*log_stream" syntax.

if(log_stream_delete) {
  ostream* t = log_stream;
  log_stream = &cout; // Just in case we forget.
  delete t;
  log_stream_delete = false;
}

--Eljay