IOstreams use streambufs to as their source / target of input / output. Effectively, the streambuf-family does all the work regarding IO and the IOstream-family is only used for formatting and to-string / from-string transformation. Now, istream_iterator takes a template argument that says what the unformatted string-sequence from the streambuf should be formatted as, like … Read more
It’s actually pretty trivial to write a one-shot std::streambuf that uses the buffer in place as the default behaviour of all the virtual functions of std::streambuf does ‘the right thing’. You can just setg the read area in construction and underflow and uflow can safely be left to return traits_type::eof() as the end of the … Read more
I don’t know whether it counts as “excessive copying“, but you can use a stringstream: std::ostringstream ss; ss << someStreamBuf; std::string s = ss.str(); Like, to read everything from stdin into a string, do std::ostringstream ss; ss << std::cin.rdbuf(); std::string s = ss.str(); Alternatively, you may also use a istreambuf_iterator. You will have to measure … Read more
The canonical approach consists in defining your own streambuf. You should have a look at: Angelika LAnger’s articles on IOStreams derivation James Kanze’s articles on filtering streambufs boost.iostream for examples of application