Tutorial 3: Setting the ostream

You can write the debug output to any given ostream.  The following example opens a file log and uses it to write its debug output to.

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Compile as: g++ -DCWDEBUG log_file.cc -lcwd -o log_file

#include "sys.h"		// See tutorial 2.
#include <fstream>
#include "debug.h"		// See tutorial 2.

int main(void)
{
  Debug( dc::notice.on() );
  Debug( libcw_do.on() );

#ifdef CWDEBUG
  std::ofstream file;
  file.open("log");
#endif

  // Set the ostream related with libcw_do to `file':  
  Debug( libcw_do.set_ostream(&file) );

  Dout(dc::notice, "Hippopotamus are heavy");

  return 0;
}

Debug code like the definition of the debug file file, should be put between #ifdef CWDEBUG ... #endif as usual.  This isn't needed for Debug() or Dout() because these macros are automatically replaced with white space when CWDEBUG is not defined.