Standard no-op output stream

Question

Is there a way to create an ostream instance which basically doesn\'t do anything ?

For example :

std::ostream dummyStream(...);
dummyStream <<         


        

Answer 1

You need a custom streambuf.

class NullBuffer : public std::streambuf
{
public:
  int overflow(int c) { return c; }
};

You can then use this buffer in any ostream class

NullBuffer null_buffer;
std::ostream null_stream(&null_buffer);
null_stream << "Nothing will be printed";

streambuf::overflow is the function called when the buffer has to output data to the actual destination of the stream. The NullBuffer class above does nothing when overflow is called so any stream using it will not produce any output.